I got a free loaner phone once a few years back ("Samsung Ultimate Test Drive") which came with pre-activated mobile phone service and was very clearly re-using a phone number that someone else had quite recently actively been using.
While it was weird to get SMSes about SoCal drug deals, the strangest thing of all with that phone was opening the Lyft app and being automatically signed in to someone else's Lyft account on the basis of my auto-confirmed phone number. Their active credit card was linked to the account and I could take free rides!
(I didn't... but it was very hard to sign into a different Lyft account when the phone # was actively linked to another, live account.)