Air travel has gotten MUCH slower in the last 20 years. I need to show up at Logan about 2 hours before takeoff for a 90 minute flight to DC. The terrorists slowed flights down much more than fuel economy on all but the longest flights.
A 2 hour flight, e.g. from NYC to CHI, is often 6-8 hours with all the surrounding nonsense. Getting from Manhattan to JFK, Newark or even LaGuardia is easily 1-2 hours, waiting in the airport, going through security etc. is another 1-2 hours. Getting through the destination airport from the moment the plane touches down and until you are actually leaving the airport with your luggage is rarely less than an hour. And then the transport into the city is another hour.
With transatlantic flights it's often 14-15 hours or even easily 20 hours if you need a connecting flight in one end, although the connecting flight is "just a one hour flight", because of all the waiting between flights.
Flying is great. Everything around it is terrible.
In the late 90s you could roll up to the airport 15 minutes before an international flight, walk to the plane hardly breaking stride for customs, fly to your destination, and walk out to the taxies -- again hardly breaking stride for customs.
Then there was 9/11.
If you're leaving the US, things probably aren't much more involved at the destination. It's when you come back that you have to deal with pissy immigration and customs officers.
FWIW, Calgary is this way as well.
In many -- probably most -- countries there is some kind of outgoing border control for any international flight -- not necessarily "customs" but something similar. (I was actually detained briefly at customs leaving Sydney for Japan in the 90s. Never found out why.)
For international flights returning to the US, at this point Global Entry is almost a must. Last return flight MUC -> SFO, if we didn't have Global Entry, we would have been in line for at least an hour. GE kiosk? A couple of minutes including needing to type in my flight details.
As PreCheck becomes more popular, I suspect some parts of flying will become a bit smoother for people overall.