The thing no one has said is that if they have these procedures in place, there may be a reason for it-- as in, bad past experiences.

Check the bike over thoroughly before touching it: avoiding having someone come back and say "you messed up my bike!" when damage has already been there. Or avoid a "knowledgeable" customer saying it's fine, and they believe the person, only to have the person complain later that "I can't believe you didn't notice X is wrong" or "something bad happened and another bike shop told me it's because Y was messed up.; why didn't you know that."

Judging for themselves what it needs: goes back to the "knowledgeable" customer who says it just needs a wee chain lube and it turns out to need a lot more than that.

Knowing before they accept the bike what it needs: no customers angry at "surprises" (or, suspecting them of trying to "upsell"). I'm glad you're reasonable if they call you and say "Hey, it needs this." Not everyone is reasonable.

With a pre-inspection, everything is out in the open before anyone feels any obligation (if the customer doesn't like what they hear, they can pack up their bike and go rather than complaining that "and they didn't tell me it needed Z before they were halfway through what I brought it in for, so of course I was going to have them do it; of all the underhanded tactics..."), and the shop's rear end is covered. I a. am big fan of CYA, and b. have seen just enough in the world to know how absolutely nuts and/or unreasonable some people can be in business situations (these are also often the ones who are firmly convinced that "the customer is always right {no matter what}" and the ones who will crow to everyone they know, and on Facebook and NextDoor and whatever other social media people have, about how crooked a business is).