I'm pretty sure that the application fee at an Ivy League school isn't seen as a revenue generator. It is more so that they get only thousands of applications rather than millions each year. People in the US with no chance whatever of admission are less likely to apply and tie up the system if there is a fee. It also helps fund the admissions system itself.
The barriers for international students are higher in any case due to travel, immigration rules, economic differences, etc. The fee waver is there to encourage more foreign students so that they get hundreds of applications, rather than tens. There would be no reason for them to prejudice an application asking for fee waver if they actually want to encourage foreign students. The same is possibly true of GRE wavers - encourage foreign applications. Most US schools and all top level schools want to encourage a diverse student body.
The GRE may also be harder to take (and relatively more expensive) for some foreign students, but without it the admissions people will need other evidence that they can predict success for a student.