I was on a flight from MSP to London (DL12) on the first of January 2015. When I got there, I didn't see any mention of the gate the plane parked at from inside the terminal. Is it because, as a U.S. citizen, I had to go through customs? I ask because recently got back to MSP from MCO, and when I got out of the jetway going into the terminal, I saw the number of the gate we were parked at (H8), and then remembered I didn't see it at London. I was looking for it, but never found it. I like to jot it down.
If you watch out the window before the plane comes to stop you may see the stand number, for the pilots' convenience, which usually has some correspondence to the gate number. For instance stand 512 at Heathrow is served by gate number A12 in Terminal 5. But if you parked at a stand with no air bridge and were bussed to the terminal, at most airports you would not have a gate at all (unless you count yourself parked at the relevant bus gate).
The gate number is simply for the benefit of departing passengers. It is not a useful reference for an arriving passenger and so it isn't displayed unless you happen to decant up the air bridge and back into the departure lounge.
Whether you are international or not is not quite the question, because procedures for separating arrivals and departures differ greatly across the world and even within airports. In many countries (including the UK and for most circumstances the US) international arrivals are segregated from all departing passengers as a matter of security; the UK government simply does not trust anyone else's security arrangements, so as an international arrival you cannot be allowed to mix with the departing passengers. It is nothing to do with customs, which happens much later.
However when you are arriving in Amsterdam from the USA, you are considered "clean" and you are deposited directly back into the non-Schengen departures area. At this airport you would see your gate as you left the aircraft.
It's certainly not the case that you weren't told the gate number because of your nationality. After all, there will have been many different nationalities on the plane so they could hardly tell some people the gate number but not the others.
The simple reason is that you weren't told the gate number because you don't need to know it. You didn't notice any signs because they're posted to make it easy for people who are trying to get on the plane to know what gate they're at.