I think there needs to be some distinction between apps that are the main product (or close to it) and apps that support another product (like there is npo point to having the app by itself, you should already have gotten the product/account before downloading the app). I don't know too much about Apple's rules to know if they use that criteria, but it makes sense to me.

An app to manage your Tesla makes no sense unless you own a Tesla. You probably (definitely?) created an account when you ordered your car, so you don't need to sign-up in app. I suppose people that could buy a used Tesla without a Tesla account, but I'm pretty sure you need to link the used car to a new account before you can manage it through the app with the new account, so it still doesn't make sense to offer in-app signup. I see no issue with the Tesla app being approved.

Some of the other apps do seem to be legitimate complaints. Netflix being an obvious one- it's totally plausible for someone to expect to download Netflix on their iPad and then pay through Apple. Netflix could easily offer that but doesn't (probably because of the 30% cut). Apple would gladly reject a smaller app, but they approve Netflix because too many users would complain if they couldn't get Netflix on their iPad.

Edit: one other thing I haven't seen whether Basecamp could just charge $141.43 per year if someone pays through Apple, so Basecamp would get $99 per year after Apple takes their 30% cut. They are allowed to offer outside subscriptions for multiplatform products, as long as those subscriptions are also available in-app. That seems like it would follow Apple's rules. People that don't care about money could sign up in-app, but most people will sign up outside the app.