If I recall correctly, the area you are in has been one of the hot spots in the province and was held back from going to stage 2 in re-opening.I do curbside pickup of groceries where they actually put them in the boot and on occasion it takes a bit of a wait which isn’t a big deal. What l do as l wait is watch who is going in and out of the stores including Walmart and Canadian Tire. On Friday evening not a single person was wearing a mask or washing their hands at the provided stations at the entrances. The bigger eye opener was the cars with number plates from Michigan, Ohio, and Penn, I am shocked we have got so far relatively unscathed.......
We don't see many American license plates here even in normal times, and I can't recall having seen one in months.
There was a story in the news a few days ago about American licence plates in Canada. If you are seeing them in Ontario the cars will mainly belong to Canadians who had been living in the US and moved back to Canada after things went down the crapper in the US, or in a few cases they will be people on essential business, or are in a few other exempt categories (e.g. international student). When they are allowed in, they have to quarantine for two weeks (truck drivers and airline crews excepted).
In Alberta and Yukon there have been problems with Americans abusing transit privileges between Alaska and the rest of the US negotiated as part of the border closure. They are supposed to go straight through by the most direct route without any unnecessary stops. RCMP have been looking for ones who are outside the permitted transit areas and have been issuing fines.
According to the news story there have been multiple reports of people with American license plates being on the receiving end of "aggressive behaviour" by locals. This being Canada rather than the US, we haven't been shooting them. Instead the "aggressive behaviour" has mainly been dirty looks and people telling the the "dirty Americans" to "go home". The recipients of this behaviour have been in tears while trying to explain that they aren't Americans.
The news story concluded with a plea to be more understanding of Americans (or apparent Americans), etc., etc. Or in other words, to not get the pitchforks and torches out whenever you see an American license plate as they may have a valid excuse. Of course that's just the usual limp wristed news reporting, and you ought to get your friends together and go patrolling for Americans sneaking over the border. Remember however that they are all riddled with plague and you need to wear the correct PPE when lynching them.