Airports and sewage treatment plants have other constraints on their locations (flat land, downstream) and it’s not just the employees who have to travel to reach them but every construction vehicle, delivery truck, etc.
But eh infrastructure is hard, Melbourne doesn’t even have a regular train line to the airport yet.
“It’s expensive” is such a big deal that often doesn’t get weighed in public arguments correctly.
If the train is twice as expensive, then society itself can afford half as many trains, and when you’re making the decision to buy that train, you are necessarily giving up an entire train’s worth of resources that not only could be spent on a train, but could be spent on something else instead (like hospitals, schools, or golf courses).
So yeah, “NIMBY” is getting used to criticize people who are opposing things society needs. However, because there are costs and they’re not currently dealt-with well, instead of doing something stupid like building a train line to no where, might I suggest insuring them for the difference in property values caused by the NIMBY item.