Fortunately, I have a great dealership - Toyota of Denton in Texas.. I have had the same service writer and tech for eight years. I have the service writers personal cell (text only) for communication, get free loaners for major work and get to go back into the shop to "brainstorm" with my senior tech. The way to do it is to cultivate a relationship with the same service writer for every visit. Make your appointments on line and request that service writer. They make a commission off your business. Ask to used the most senior and experienced tech for all your work and get to know them. Perhaps a six pack or ball game tickets. Don't expect the senior tech to do oil changes, but ask for them to do the multi-point inspection at the end of the oil change. Be polite and patient. I usually wait for my work at the dealership, but not everybody can do that. Don't abuse the privilege of free loaners. Bring all your Toyota and Lexus vehicles to that dealership and funnel all that work to the same service writer and tech. Yes, my dealership (and other Toyota dealerships) will work on Lexus vehicles, and it cheaper too, but you don't get the free apples for the horses and the free lattes and peanut M&Ms!
Regarding verifying work done, back in the early '70s I was known as the "mad tire marker" at Bob Sharp Motors in Wilton, CT. I used to mark the inside of the tires to verify that they had been rotated. I also took my pocket knife and scraped off one letter of the manufacturer's name on the oil filter to confirm it had been changed. Finally, you should be able to pull the dipstick and just look at the oil to know it was changed. Should be nice and light.
I hope this helps some members.