I mean, say, you want a really nice camera, or a drone, or maybe a gaming laptop, and since those things are made in China, they are too expensive to buy right now in the US, since tariffs are over 100%. So you just go to Canada, buy the thing, unpack it from the packaging, and pretend like its just personal items. Just like a smartphone.
AFIAK, border agents usually don’t ask if you bought your phone in the US or from outside, they shouldn’t ask about other personal electronics, right?
My understanding is that the de minimis tariff treatment for import shipments is different than the duty-free personal exemptions that apply for “accompanied baggage” when re-entering the USA and has the imported items with them.
Assuming this CBP page is accurate, the $800 exemption is one of three possible exemptions that can still apply. The $1600 exemption only applies when returning with stuff from Guam, American Samoa, or USVI, and the $800 can only be claimed every 30 day. The last resort is the $200 exemption, which is always available, and ostensibly is there to allow Americans living near Canada or Mexico to not have to deal with border taxation just because they had to buy lunch or gasoline during day trips.