In 2016 there were tens of million of Americans who couldn't absorb a sudden $400 expense without going further into debt.

That number's probably grown significantly since.

Drop in the bucket compared to the cost of travel. Your point still stands though.

It's also convoluted process too. If you never had passport or haven't renewed in like 15+years you have to reapply, and then set up a whole appointment, most are booked months it not longer in advanced and only specific location USPS in your area. The scientists currently emigrating to Europe are already well off individuals( that's why MDS and scientists are considered well off peoples degrees), certainly not poor