I had a connecting flight in MEX coming from IAH on my way to a different country. My layover was less than 1:30 hours. It was interesting to me all travelers are required to go through immigration even if you're not visiting MEX.

It seems kinda pointless and a waste of time and money.

I know this is standard at US airports, but are the many other countries doing this nowadays?

It happens in the EU at the first airport where you land coming from the US even if your destination is elsewhere.