No good excuse? People not being able to see their loved ones if they are sick, being stranded abroad, losing their jobs or getting thrown out of their education?
I'm sorry, but there are plenty of reasons. If you can't see how doing what more successful countries in lockdown's have done then that is silly. UK never shut its borders, fine, but they never did any requirements to enter. Almost all lockdown success countries kept travel restricted, not closed. You don't enter without a PCR test, you do one at the airport, you stay at a government hotel during quarantine etc. If people who are willing to travel with all these checks (at their expense), I can guarantee you their travel is essential