Let's take an example round trip flight from Boston to LA. I've flown this many times for work and to visit relatives, and it's maybe on the long end for a vacation flight. Taking into account that emissions at high altitude are worse than at ground level, that's about 1.3T CO2e [1].

The thing is, 1.3T isn't that much! For example, carbon offsets are about $10/T, so this would add just ~$13 to your ~$500 round-trip flight. Or, if you don't trust offsets and would rather use the full social cost of carbon, that's ~$55/T (Wang et. al. 2019) or ~$72. Or, if you want to go all the way to direct air capture, that's ~$160/T (Keith et. al. 2018) or ~$210.

If you consider a typical BOS-LAX business trip, with, say, $500 for flights, $500 for lodging, $100 for food, and 14hr time lost to travel, a carbon cost of even $210 is rarely going to make the difference on whether the travel is worth it. Even for a vacation, where people tend to be more price sensitive, it's a factor but not nearly the biggest factor.

Climate change is a real problem, and I'm not saying we shouldn't change anything. I favor a stiff carbon tax, high enough to cover the full social cost of emissions. But even under a high tax, most of the things people fly for today would still be worth flying for.

[1] I tried three different calculators and got 1.16T, 1.4T, and 1.36T.