Never.

It’s happened 2 times in my many years of adulting.

First, tried to buy a laptop with shipping address different from billing address. Called them and confirmed I was not a scammer.

Second, bought propane at a gas station, then tried to buy gas. I’m guessing multiple purchases at a gas station indicates stolen card about to run a scam.

The merchant gets charged back for fraud which is why they care.

Chase routinely flags my phone bill that I’ve been paying to the same company for 5+ years as “potentially fraudulent” and doesn’t allow the purchase to go through.
However, they didn’t flag a $900 purchase on Chipotle gift cards on the other side of the country as potentially fraudulent and I had to file with them and wait for them to complete an investigation.

Twice. Once when I was buying large appliances which I basically never do and a call to my bank cleared that up, and once trying to buy a video game directly from the company (instead of say through steam or gog) and going in to the bank fixed that.

Retailers do it because they pay a penalty when a chargeback happens and payment processors will cut ties with them if their fraud rate is too high.

Never. What are you doing?

Never. Not even when I saw fraudulent charges on my statement and reported them to my bank.

Some 20 years since I moved from home and I’ve never been flagged.

Only happens when I order something twice in quick succession

I’ve been using protonmail basically since its inception for money-related stuff (due to it being secure), and the one time I’ve had a fraud flag appear while using it was due to being on a VPN at the same time.

… But I’ve had that also happen when I used to daily drive Gmail, so I can’t imagine the Proton part made the difference.

Obviously anecdotes aren’t very good evidence, and maybe in your experience it was your email - but if that is the case, I’d be weary of any provider that automatically flags non-“big tech” addresses as fraudulent. That likely means they’re rather lazy about their cybersecurity.

It happens to me every time at dispensaries and strip clubs. I guess it’s pretty obvious why.

I’ve had it happen when buying gift cards online from Costco. Definitely annoying

Never with “everyday” purchases. The two times it happened to me were a VST plugin and a game engine license.

(I’m also in the US with a nonwhite name.)

Especially when the retailer does it. Like wtf dude, why do they care if its someone spending their money legitimately, or if its stolen, they get money either way. Is this some weird “we stopped fraudsters” PR campaign?

Sometimes people just try to do the right thing

Haven’t had it happen yet…