I know some people who traveled at Christmas, then one of the people they were staying with tested positive, so after days of being exposed they ran to the airport, jumped on a plane and flew home. This is the selfishness you're up against.
Someone in our family is a NURSE!!!!!! Who lives in Florida and has not been able to stop complaining about how non-seriously everyone there is taking the pandemic this WHOLE TIME!!!! And then her and her fiancee went to MA for a wedding, got positive covid tests while there, and FLEW HOME!!!!!! The test results ended up being false positives, but that in no way invalidates all the exclamation points and capital letters I used in this post. I'm really hoping there's more to the story that we're not getting that takes this from insane to understandable, but I'm not sure there is.
Edited to add: AND!!! AND!!! They were staying with her dad, who for complicated and long past small business reasons, basically owns two houses next door to each other. Would have been easy and free to quarantine for 2 weeks in MA.