2006 Suzuki Forenza Mechanic no rotate tires and often lose

Sorry this really more about car maintenance than car repair...

How can one be assured that a mechanic really performs all the maintenance work specified? Or we just need to have faith/trust and find a really good dealer/shop?

I'm just asking as today I took in car for 30k mile service & before taking car to shop, I minutely marked the tires to note their positions. After taking car back (after leaving the dealership already unfortunately), noticed they were in same positions. Also noticed spare tire was in exactly same position as I had marked it. If I didn't mark the tires, it would be harder to tell, especially by a novice like me. Do you think my marking them is a good idea or is that going overboard or showing you don't trust the mechanic? Makes me wonder whether they checked the tire pressure on the spare, unless they check the tire in place in the trunk or are very attentive to positional detail, or just happen to put it back in same position.

I saw this thread online about rotate vs not rotate tires:

http://www.f150forum.com/f38/dealer-service-dept-didnt-rotate-tires-because-front-tires-have-more-tread-36115/

it's kind of interesting to me. My tires don't appear to have uneven tread wear, so it's not as critical.

Here's the interesting part for my case though: the papers I got back say the mechanic rotated the tires, and that the "better" tires are on the front. Following the other thread above, could that mean mechanic felt the front tires were already better than the rear so didn't do the rotation?

On a related note, maybe I just have some bad luck or go to the wrong dealer/shops, but several times at this dealer and once (so far) at one or two other dealers (for other family member cars), when we get the car back after service, there is always one tire valve cap missing. I never recalled getting missing caps when I used to take old used cars to the third-party non-dealer shops. Is this something common for dealer shops to lose? I made a complaint once and the mechanic gave me attitude that the tire was already missing cap when I brought car in (when it wasn't). I don't bother to complain about this anymore as it isn't expensive to replace myself.