Would you mind to share your stories/experiences of your own cases of reverse culture shock?

I can start. After recent weeklong California vacation it came shocking realisation to me how expensive US in general and California in particular is, pretty much on everything - lodging, car rental, food, attractions, you name it. Heck, $20 fee to taste four different wines now is considered normal...

If for some (not so good) reason I have to go back to US, California and Bay Area specifically would not be the place to settle down.

P.S. And don't get me start about traffic... 35 min to drive from SFO to San Mateo, that's 7 miles.

Interesting you bring up wine. That's a good example for me.

Recently spent the better part of a month in three different European countries where we bought all sorts of excellent wines for 8 to 10 euros a bottle. In the U.S., most of my favorite California wines are $40-50/bottle and even good everyday drinkers are usually $20+. I'm sure if I got to know more of the European brands I'd be finding good everyday drinkers for 5-6 euros.

The state of US transport infrastructure. Given our national aversion to reinvestment in shared resources we have the airports and transit systems we deserve, but it is a regular shock for me to return from Europe or Asia to a US airport that is dilapidated, understaffed, overcrowded, cracking and leaking, etc. and then use a train system that is literally crumbling before one's eyes. Londoners in particular complain endlessly about the tube and regional rail, but stand them next to nearly any US system and they look like gleaming Asian modernity. And the Asian systems? Japan, Malaysia, Hong Kong, China? They look like science fiction.

Our national boosters chanting U-S-A, U-S-A! who keep insisting we are the greatest country in the world by every measure... are ignorant, willfully or not. On infrastructure and other counts, we are falling apart and heading for third world status. It amazes me how we not only live with so much decay, decline, and neglect, but eagerly defend it as the world's best. Only international travel brings this truth home.

Every time I return to the US from a work trip to Japan, I'm shocked at how loud Americans are on public transportation and in public spaces. I realize Japan is probably an extreme case, but I always appreciate how quiet full trains are. No unnecessarily loud phone conversations, no practically yelling at someone who is only arms-length away, nobody playing youtube videos without headphones.

returning from a trip to japan the gruff "find a seat" at an airport tgi friday's was a bit of a shock after a week plus of japanese customer service

Landing at LAX after being in Tokyo for a week. Haneda was all bright and airy and the Tom Bradley terminal was just dark and dismal.

While the certain stuff - like difference in efficiency/state of public infrastructure can be observed after short trips overseas, what I wanted to mention that most cases of reverse culture shock cases come in light when one spends significant - let's say more than a year - time away from home country.

To me with above mentioned expensiveness, loudness was the second thing which was very easily to spot. During dinner at restaurant we could hear a conversation at a table across the hall.

Other thing which become noticable, sorry for pointing this out - how large (or you can use your own word) people are. And that in Bay Area, which probably is not the worst case if you take US in general.

I would say that this phenomenon largely affects China and on lesser degree Singapore, Korea and Hong Kong.

Correct. And this is one of (along many other) topics you can't easily have conversation with locals. But we are getting offtopic here.

Three observations, two recent, one not.

First recent: THE TRAINS! Whatever can one say?
We were just in Italy, and once again, their Fast trains are... fast... and comfortable/smooth.
And 2 years ago, in Japan... we will NEVER forget the first time we were waiting in a station for a train, and fortunately (or we would have missed the full experience) it was a station where most bullet trains did *not* stop. So, there we were, waiting to see one, as we had time to spare for our local train... and then suddenly, on a middle track...
SWOOOOOOOOSH!!! ... And... Poof! it was GONE..!

Yes, Sci Fi category, first time experiencing that

Second recent: Different level of "security" at times.
While we were waiting for the train as described above, two sharply dressed me arrived, and stood right in front of a "gate". (There are barriers so one doesn't walk/fall off the platform, and the doors stop in *very* predictable places so that gates line up with the doors.)
We had someone who had taken us to the station, or we may have missed the entirety this.
When the train stopped, right in front of us at that gate, several other men emerged, looked each way, and then a woman got off, greeted the two men waiting, and they left. It was the First Lady (Prime Minister's wife) of Japan. No huge fuss, but some reasonable precautions.
We would not have recognized her, had we not been told. But no disruption to others, no major pomp, etc.

Long ago: After living in the UK for a year, without returning to the USA during that time (although traveling a bit in France, Spain, and Italy on little vacations), upon returning to the USA, the overwhelming COMMERCIALISM OF EVERYTHING. Bright neon lights advertising any/everything thing. HUGE billboards everywhere... It seemed that one really couldn't quite "see the forest for the signs...!"

GC

Before we get too carried away about the superior airports and some other infrastructure outside the US let's keep in mind that the systems that produce this also lead people to fly across oceans to go shopping.

This is because you were in California. This is not true for the US in general.