Because it’s a major pain in the butt!!! You can only set up testing 2-3 days in advance which makes it’s hard for no retired people. Or setup testing at a walk in clinic, and while the testing is free the “dr visit” gets a copay. Which is weird but last time I had met my deductible so didn’t mess with it. I would do it this time as a back up in case the other doesn’t work. I use these tests to come home without an issue. I have two trips scheduled and then another in February with my “cape cod kid”. And if she she can do this it would be fantastic as testing is awful out there!!!