In Islamic/pre-Islamic mythology (over simplifying greatly) genies are actually trapped demons forced into servitude long ago by human sorcerers. They must comply with your wish but use any ambiguity they can as a form of malicious compliance. It's also worth noting that the idea of genies granting 3 wishes is mostly a western invention and is also likely influenced by Christian ideas of "deals with the devil" (see Foust for how that usually works out for the wisher)

Because to the Genie it's hilarious.

"You shouldn't be fighting me, Perry the platypus. You should be fighting genies. Genies are the problem"

In Germany we have a word for it. Schadenfreude. translates to something like malicious joy. Basically the pleasure at someone else's misfortune.

I suppose it depends on what lore you're using.

If you're using Wishmaster rules, it would be most efficient to just do what they want with no ironic twists and then get your freedom to reign terror unexpectedly after the 3rd wish.

If we're using Disney Alladin rules then the master must explicitly wish for the Genie's freedom or else it's trapped in the lamp forever. In this case it makes some sense to twist things as it would be the only kind of control you could exert.

In Quranic mythology, I think the jinn are mostly independent magical creatures that are purely neutral. In these cases, there are no real stakes for freedom at play, so every request would be played by ear.

It always seemed like a logic gate thing to me, like the Fullmetal Alchemist rule of equivalent exchange. Otherwise, there comes a point where there would be no order or structure to the universe and the benefit is boiled down to simply preserving reality.

Also talk about inefficient.

Why burn a 4th pevel spellslot for polymorph, when a simple jump spell would have done the job.

Maybe its like the Needful Things episode from Rick and Morty where its in the devil's nature to fuck with people foolish enough to trust him. Even Summer.

Not everything is a trade. People do things because they like it, or out of any other emotion. It's capitalist philosophy that pretends everything is a trade and that you must earn something for anything you do.

Check out the Wishmaster movies. The first two are quite enjoyable campy horror comedies, 3 and 4 not so much.

You wish for the genie to be free. Turns out to be the worse curse of all.

It's funny that's reason enough