(USA resident here) I've made several high value purchases ($100+) online without getting an additional 3D secure prompt. However, my credit union is rather liberal in locking my card for what they think are suspicious transactions. It's a text or call to customer service to unlock (where they verify recent transactions), but I'd rather enter a password more often than have my card randomly locked.
Actually it's possible you did get a 3D Secure prompt, but many US banks don't do anything with it and just instantly redirect back with authorization.
It's impressive how far behind US financial institutes are.
I've been with the same bank for years, and I will occasionally get one (once or twice per year). I shop on the same sites, too.