I don't know for sure, but my guess is the subscription service is likely to enable features that require cellular access, and that's what the fee goes to pay for - similar to GM's OnStar system. Things like remote start, unlock, check status, etc. from anywhere in the world, not just beside your car. In that case it makes sense, and again, my guess is that people who are making videos about this aren't telling the whole story or don't actually understand what the service gets you.
EDIT: And here you go:
Toyota's remote start system will require a subscription to operate, even for the functionality built into the key fob.
www.autoblog.com
"We should explain that there are two ways to remote start Toyota vehicles. One is using the fob, a chip in the key sending a radio signals to a chip in the car to let the car know to start. This one relies only on proximity communication between key and car; typically, as long as the fob chip, fob battery, and vehicle chip are in good working order, all should be well. But that's not the case here, which we'll get to. The second way is by using Toyota's Remote Connect suite of services that costs either $8 per month or $80 per year. These services operate through a cell or wi-fi connection and include remote start, finding your car in a parking lot or finding PHEV charging locations, monitoring teen drivers, and locking or unlocking the car."