If the consumer likes your service, rest assured at the end of free trial, they may be slightly annoyed but will quickly renew their service to make sure they can continue to have access if they have to. A card associated with my Netflix account expired and I didn't realize, it was renewed within 10 minutes of me wanting to watch a show.
If you're forced to go through a process to renew something, you're more likely to question why you're going through the process and if the service the process exists for still maintains value to you worth continuing payment for. Businesses are aware of this and attempt to avoid those situations. Minimize friction of revenue, limit any barriers for money flowing in.
It's very intentional and I've yet to see a good argument for trial-to-subscription auto opt-in that is not a strategic money grab based on a probability of unintended customers. Many decades ago, magazine subscriptions were notorious for this exact same predatory subscription lock-in model, even making it difficult to cancel (while incredibly easy to enter).