I've never had trouble explaining discrete codes to customers. Sometimes I get to techie and see the glass over but I like to try to be detailed but not overly technical after a simple explanation. Like Ernie said all you need to do is implied is why it is important for the customer to always either purchase product from you or get pre authorized model numbers.

I usually use the power button as an example explaining that when you press the power button on your remote the remote doesn't know if your equipment is on or off it just changes toggles between the two. Manufacturers build IR commands that are just on and just off. So if I send an on command it will only turn on. Without these advanced codes we can't program the remote to just turn on so when you hit the DVD command your TV might turn on or might turn off and your receiver might turn on and might turn off.

If a unit doesn't have discrete on or off there are several ways to detect if it is on or not and they are all over this website. current sense as tpowers pointed out (niles, xantech and for a real hack smartstrip), light sensor, video sensor, USB out, I'm sure there are even more. After explaining the toggle commands you then talk about these items and how they are going to add to the over all cost of the product so you saved $150 by buying insignia/vizio instead of panasonic/samsung/lg but now I have to charge you $500 so you can operate your system.

And if you can't sell a universal remote in every system even with the added expenses you need to start looking for a new job. "What's the point of putting in an amazing home theater if everyone in the house can't use it?" sacrifice everything else before control especially with how inexpensive it really is to get entry level stuff.