In his defense, you did say "Work that they DID" as in past tense.
We do have schematics that are only to be maid available to BBY Employees in the correct job code (i.e. Autotechs) and we are NOT to give these schematics out to customers as it violates our agreement with the company who provides them. We pay for them as a company, as would anyone else who wants access to such information. When installing the security systems, we do go through line by line (sometimes with a highlighter as that is what I make anyone I teach do) and verify the wires with a DMM before soldering a connection in to the vehicle. I'm not sure where you recieved your information as to how we do our installs, but it seems it was way off. If the shop in your area does not call their appointments the night before to remind them then they are not following procedres.
And anything we install comes with a lifetime warranty on the workmanship. This means if there is a problem, we will remedy it at no cost to you. This DOES NOT cover all product we install, but we don't try to "hide evidence" of our installs. We do have to keep tight lips about where we place certain connections and the reason is because we do not want to run the risk of someone going in afterwards and trying to mess with them. If this is done, it is a direct violation of your warranty terms and conditions which will void the warranty. We are a business, and not a charity. We do not stay in business by giving things away for free or by not offering our services.
Just remember in your travels, if you cancell your appointment with BBY and have a mom-n-pop shop install your equipment Directed Electronics may not honor their own warranty on the product. They only give out the Lifetime Warranty when the system is installed by a professional and authorized shop, not one or the other but both.
I hope this helps clear things up as to how we conduct buisness and why!
While I am employed by Best Buy for the Geek Squad Automotive Technicians, my responces are strictly my own and do not represent those of Best Buy formally or informally.