This stinks of dark patterns and maximizing the amount you can hit people who forget to cancel for before they notice. It's rather unlikely that someone would actually want to pay quarterly at the higher monthly rate.
This very clearly IS a dark pattern.
The important bit here. There's no tricking going on. It's all clearly stated when signing up for the Free Trial. You're just being obnoxious.
If you think I'm being obnoxious you should perhaps reflect on your own behavior. Others in this thread clearly agree that this is a dark pattern.
You're defaming one of the most beautiful services that has ever come out of YC. A service that will help the life of so many hardware hackers and professionals. The pricing model for InstaPart is the most noble I've ever seen and you're complaining about them being predators and dark pattern practioneers?
However, we don't ask for credit card details until the first payment, so, there's no risk that a user would be charged accidentally. It also reduces onboarding friction as a credit card isn't required for signup. If a user doesn't want to continue after the trial, we advise them to disregard the invoice.
This is why this is pretty standard practice - keep sending reminders every week and also the day before you are going to charge.
I (an engineer) have gotten subscriptions for things that would never have gone through if I had to go through and file a report on why this should be bought.
Also, not making a credit card mandatory for sign up will get you non-serious customers. You will need to have infrastructure costs to support a large number of these.
I'd argue that it would add some amount of inconvenience to the user, and lower conversion rates as a result, if the user has to pay to continue using the service.
It's predatory.