I mean, say, you want a really camera, or a drone, and since those things are made in China, they are too expensive to buy. 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?
I live a few miles from the border and cross at least weekly. You could generally get away with this for a handful of things, especially if you’re smart about it (dispose of all packaging and tags, have an otherwise legit reason for a short visit, etc).
But if they question you, and they determine you’re intentionally lying about it, you can expect to pay additional fines and lose several hours of your life.