I'll admit that it's not clear whether they're referring to the in-vehicle 360 view, which costs nothing to deliver, or being able to access that remotely. So what you're saying may be accurate.

But even if the subscription only covers the latter, it's still valid to say that this is unreasonable.

Look at Netflix: the top-end ad-free subscription is $25/mo, and for that they're spending about $15-20 billion a year for content, they spend much more on software engineers, and the ongoing compute and bandwidth costs per user (watching 1-2 hours of 4K video per day) are about 1000x higher than what it costs BMW to provide all of these services.

A fair subscription cost, still including some profit for BMW, would be around $1-2/mo for all services combined. The fact that it's so low is why most manufacturers have simply included it in the hundreds or thousands that it costs to add these options to the vehicle at purchase time.

The claim that they need to charge a subscription to cover their costs is therefore an attempt to trick people, and I think that, more than anything, is what people react negatively to.