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?
If you remove the Luxemburg, Andorra, and a couple of smaller countries, VAT rates are relatively consistent. Indeed, if you live within 20km from the border, it’s worth buying some stuff across the border, and for some trips to plan a fuel stop on the right side of the border.
But if you need to drive 100 km, you won’t recover the cost of the road if you don’t do some specific purchases.
Note also, that at least in theory, you’re not free to travel with unlimited cigarettes and alcohol (where tax rates difference can be crazy) so again, if you pass by Luxemburg or Andorra, you can’t legally speaking buy 100 packs of cigarettes, (but would still save 30 to 50 € on a 10 packs carton)
From Switzerland shopping in Germany is pretty worth it. Their VAT which you can claim back on export is 19% ours is 8.1% and on top of that their prices are generally cheaper. It’s a real thorn in the side of Swiss retailers. They successfully lobbied to have the VAT free value lowered, starting this year it’s 150 CHF instead of 300 CHF.