easy.

There is no "technical reason" to go to a dealership for an oil change. You can do that yourself or a mom and pop.

The biggest advantage to a dealership is if you are troubleshooting and issue, specifically an electrical one, as they will have access to all the dealership diagnostic and mechanical tools to do the jobs and like DirtyWater says in his post easier access to parts (and higher quality parts).

The downside is you'll pay more for it though, but most Toyota dealerships will give you a chilled bottled water. There is that.