Out of curiosity, what do you think of the pattern where a SaaS provider says, "Give us your credit card and you'll automatically be charged after a free trial"

Out of curiosity, what do you think of the pattern where a SaaS provider says, "Give us your credit card and you'll automatically be charged after a free trial" vs. "Don't give us your credit card, you can upgrade any time"? The former might be okay if the SaaS provider sent an 11th hour email saying, "Hey, last day of the trial. Charging starts tomorrow!"... but most don't. What percentage of SaaS trial users forget to cancel? That's always fallen into my "slightly shady" camp, but I can say with some authority that it's a huge needle-mover in terms of revenue.