You’re aware that the U.K. countries, Germany, Ireland, Spain, Switzerland, Hungary, Poland (does have postal voting) are in Europe, yes? Those and a few others use postal voting. This is a normal thing - no fraud, as in the US election. Voting in person is the norm, as it is in most places, which should go without saying. Currently France and other countries who don’t usually allow postal voting (although almost every European country does allow postal votes under certain limited circumstances) are allowing it, for obvious reasons. No fraud. No fraud in the US, none in Europe. Basing your idea on something you think might have happened 40 odd years ago doesn’t strengthen your point.
There are a lot of countries in Europe, and some don’t have the well developed infrastructure needed to organise a range of voting options as effectively as somewhere like the U.K., or Germany, but the US doesn’t have that problem.