I guess if you signed up for a cell phone contract and didn’t pay after the first month, and didn’t have a billing method set, it would go to collections. Things like that are generally uncommon though. It usually only happens with things like medical services, loans, auto repair, home repair/contractor services, and contractual services such as cell phone plans and utilities. (Contractors and mechanics may actually take out a lien.) Usually this only happens when there’s larger sums of money at stake or when it’s a large company with an airtight contract and a well-staffed billing department.

Things like consumer software subscriptions don’t usually involve this risk, there have been exceptions but consumers don’t like it and tend to punish it.

Even if they sell the debt to collections, the collections service is probably only going to pay them fractions of pennies on the dollar, since "bill for random service someone signed up for the internet" is not likely to have a high recovery rate.

I always expect a failed billing or no billing info after a trial to cancel and not be pursued (I regularly do trials with a temp card that I immediately de-activate so it cannot be billed in case I forget to cancel)