That's why a secondary market of lawyers and agents for pact negotiations would be formed.
We have ambulance chasers in real life. You think we wouldn't have pact lawyers?
Pretty much everyone gets injured at some point in their lives.
How many people, even in stories, make a deal with a devil, fey, or otherwise?
Markets only matter if there's enough customers to make it worthwhile. Though that does bring an amusing memory to light.
Also worth noting: You're spending an awful lot of time on Warlocks without even touching every other class, gaining of XP, the inherent ridiculousness of skills, and the fact that it means level 20 characters can fall from literally any height and survive over 50% of the time.
Plus Racial and/or Cultural traits, inherent spellcasting, and the HILARIOUSLY dangerous process of figuring out how to -do- Magic in the first place which would result in just SO MANY accidental deaths as the first wizard to figure out the correct gesture/word combination for Fireball sets one off in his office building at work and kills all his coworkers within 33,000 cubic feet.
We. Would Not. Know. The Rules.
Even if we knew everything in a single contract we wouldn't know all our Invocation Options as a nice list of pretty powers on a Menu we get to pick off of. You just -get- them, narratively, based on what the -player- chooses while leveling up.