If its a rental, they don't want to pay top dollar. All they are looking for is a receipt that its been "professionally" cleaned, ie cleaned by someone they had to pay.
The landlord is just looking to make it look clean for the next person coming in by spending the least they can.
I groom when I apply protector. Doesn't happen often, if at all, on a rental.
The truck mount is designed to wash the carpet, not suck all the dry particulate out. Two totally different processes. I've watched a guy trying to
RX20 sand out of carpet; he wasn't getting very far. 10-20 min with a vacuum and he would have saved himself 10-20 min with the truck and a lot of brown looking carpet.