I believe the requirement for fully vaccinated Americans to yet require a PCR test and the required 'ArriveCan' registration, did the idea in...
This has already or likely will become a political issue and is not a health related issue. If the Americans were really concerned about the coming and going of day-trippers across international borders, one only has to look at the border cams in Nogales. Thousands of Arizona folk coming and going as they please, lineups blocks long on a Saturday, Arizona folk heading into Mexico for fun n sun down in San Carlos or Guaymas.
i know... a few weeks ago I joined the lineup, drove into Mexico, didn't even slow down. As a Canadian going into the USA.. barely looked at my passport.. said "have a nice day"