In Denmark, we can now pay postage online and simply print the code (a string of letters, of all things?!) to the envelope instead of buying and sticking a stam

In Denmark, we can now pay postage online and simply print the code (a string of letters, of all things?!) to the envelope instead of buying and sticking a stamp. On the face of it, this seems like progress, but I do not like it, it feels off, it feels unofficial illegitimate. Like, what happens if someone takes a picture of my envelope and decides to use my code to send a letter? Whoever gets scanned first wins and the other gets rejected I guess.