Apple doesn't repair logic boards, if you have a bad backlight controller on your MacBook Pro and it's out of warranty you can expect to pay $700+ for a logic board replacement - repair shops can replace the backlight controller for a much more reasonable fee.
Right now Apple products are the most popular market for these 3rd party repair shops exactly because Apple charges so damned much for out-of-warranty repairs, and they work in a legal gray area because Apple won't give out board schematics or sell replacement components. Without schematics troubleshooting issues ranges from anywhere to a pain to impossible, without parts anything that can't be readily sourced from a manufacturer (thankfully they use bog-standard Texas Instrument controllers for the LCD backlight that you can buy reels of, but other components like the SMC, GPU, etc. you are pulling off boards that were dumped from the factory or if you can somehow find "new" ones the chances that they are DOA is dubious since they're often factory rejects).
Nobody wants to make life more difficult for companies designing their products, the Right to Repair crowd just wants to be able to fix their own devices provided they have the skills to do so.