Lucky you. Your experience is not universal.
Any vaccine runs the risk of a severe local reaction; it is in the nature of the physiologic reaction the vaccine is being used to induce. And tetanus vaccines tend to cause more frequent and more severe local reactions than most others.
As for the nurse saying that “these shots don’t hurt anymore”, well that’s just not borne out by clinical experience. For some they may be nearly painless, but local reactions are still common.
You had one tetanus shot a week ago. I’ve authorized and ordered hundreds in the last few years alone, and dealt with at least a dozen local reactions. But feel free to think that your expertise outweighs both mine and the current medical literature in this area.