Hey, 
I went through some of the ways again and it does appear you are right.
A decent amount of them are paths, not residentials, so I assume they shouldn’t have service tags.
For the residentials, someone appeared to have changed highway=service, service=alley to highway=residential and hadn’t removed the service tag, you can decide if you want to revert them to service=alley and highway=service or only revert my changeset.
Thank you for your concern, and happy mapping!