For one, it's unreasonable to assume that all of these students have home environments conducive to do high-def teleconferencing on American time zones.

Would that not also apply to domestic students, even the international students as America has very very spotty broadband access even in cities one section may have great service and go 2 streets over and you get crap...

I know locally that has been one of the biggest stumbling blocks for the local schools, dealing with students that did not have good internet.

Very spotty is different from non-existent.

Timezone, internships and cultural exchange.Also some international students are actually on merit based scholarship.Internet connectivity is also really bad in most third world countries. I can go on and on.

Can confirm, internet connectivity is really bad in many parts of Germany

A few comments already pointed at Timezone differences (which, OK, maybe it doesn't matter if courses are recorded and can be taken asynchronously) and Internet access (it seems to make sense, but I don't know if it isn't a little cliche to assume these students automatically come from very poor countries without internet).

Another I can think of is possibility of re-entry. Last time I heard the USCIS was virtually frozen for visas and all. If these students leave for this year we don't know if they'll be able to come back once the pandemic is over.

Internet connectivity, time zones, and costs of travel that can be thousands of dollars.

For merit students with scholarships it is almost impossible to finance a both-way trip on such a short notice.

We really should just be making whatever accommodation is necessary to reduce travel. The last thing we need is tens of thousands of students flocking to the airport when their visas expire. If you went home, you stay home and continue from there. If you're in the USA, stay put.

Timezones, connectivity, can’t come back (embassies are all closed) even if it reopens, still numerous travel bans, unsafe travel... Also many couldn’t get their funding (TA/RA) or scholarship without being in the US

The difference is that we can assume that this online-only move, unlike enrolling in an online-only university, is temporary. It does not seem reasonable to kick students out because one semester is online. It's extremely disruptive to be forced to get rid of your housing, figure out what to do about your belongings, and move across the world just to invert the move at the end of the year.