Sorry to hear you had such a terrible experience. I am curious about the thinking behind your statement quoted above; do you believe customs enforcement is supposed to take less time because the passenger has cleared passport control (immigration)?

Not sure I follow your question. Everyone waiting at customs has by default already cleared passport control/immigration.

But if you're asking whether customs enforcement should be quicker for MPC users just as immigration is, then yes. If you'll read through the thread, you'll see that at most if not all other airports where MPC has been adopted, there is a separate MPC line for customs just as there is for immigration. That's not (yet) the case at EWR, though.

I read your statement to imply you feel the wait to clear customs took inordinately long even though you had already cleared immigration. Put another way, clearing customs should not have taken 30 minutes because you had already cleared immigration.

But maybe what you meant is that it took 30 minutes in addition to the wait to clear immigration.

Well it's nice that some airports do have MPC queues, is there really a reason that MPC users should be given preferential treatment just because they decided to fill out their declaration on their phone instead of paper or APC?

While those on FT don't appear to agree with me, it would seem that CBP is listening: I got a nice note of apology back after leaving my experience as feedback via the app. Apparently EWR is lagging in terms of adding dedicated queues for MPC users in customs, but the intent is for the experience to mirror other airports soon.

Yes there really is a reason why MPC should have a separate line, whether or not someone considers it "preferential".

I'm flying into JFK tomorrow. Anyone know if MPC is worth it there? Do they have a separate customs line yet?

Yes, it's worth it.

At BOS, ORD and JFK this month for my travel parties, MPC has been nearly as fast, as fast as, or faster than GE. But I still find GE has an edge over MPC overall.

Thanks, I think it did save some time at JFK today. They need to improve the signage at T7 though. We had trouble figuring out which lane we should be in (it's the diplomatic/APEC lane). Also, only one officer working there, and we were stuck behind another passenger who took a while to screen.

Aside from that, it was a time saver and you do get to use the GE line at customs.

I was going to get Global Entry, but keep putting it off. Often I am traveling with others, so that kind of defeats the purpose. My last trip was kind of last minute, so I didn't have time. I signed up for Mobile Passport, and I was in for a pleasant surprise. I thought it just helped you through Immigration, but it got me front of the line for Customs to. :)
This was in Orlando. The Mobile Passport sign for Immigration seemed to be hidden. Apparently it was a the front of the line, same line for GE, I think. I was directed to that line by another person working the lines. When I got there, I went behind the people already waiting for the immigration counter. However, apparently the couple were "normal" status, and the officer told me to go ahead of them because I had mobile passport. So, I was first at the baggage carousel. (BA flight from LGW-MCO). Of course, the BA agent in LCA (Cyprus) did not put a priority tag on my bag, so it was quite a wait. However, after getting my bag, I spotted a Mobile Passport sign (also next to a GE sign) and NOBODY was there. This was, by far, my best experience ever entering the US.

MPC gets special customs line at most -- or maybe even now all -- airports with MPC. They need MPC receipt scanning devices for the passport control and for the customs functions, so the scanners for the phones' MPC receipts most commonly mean that the regular customs line is not the one used by MPC users.

MPC and families
 

It looks like our next entry into the US will be through a MPC airport--how does it handle family groups?

And will it actually do us any good as there's a 100% chance that I will be answering yes to the food question?

What is MPC?

It might help to say what passports you'll be using. Also, what does family include? Just spouse and kids under some young age or adult children, extended family? USA permanent residents?

Mobile Passport Control.

As to "food" it all depends what you mean. If it is "food" which you are 100% certain will not kick up a fuss, go ahead and use it as you may not be diverted to Ag at some FIS (you haven't told us your POE) if your initial answer is something simple such as a pack of crackers. Also depending on specific layout, cutting off the line through the immigration aspect may well speed your processing time even if you are send to an Ag secondary.

MPC works just fine for families with just US and/or Canadian citizens in the family travel party.

It works well even when declaring food. Some airports with MPC even have a special post-baggage claim line to access customs; and in some places it's the same line as GE members use.

If you specify the MPC airport, maybe I've been there and can tell you more.