I am living in UK atm where some regulation allows claiming certain amount based on distance and delayed hours. I was entitled to more than flights cost for a delayed Turkish Airlines flight.

I used an online service (airhelp) to claim it. They initially took 35% as their fee. After around 4-5 months the airline rejected the claim and lawyers from airhelp stepped in which made their fee 50%. It took 7-8 more months, total 1 year, to get 50% of my claim back (~800£) using a third party service.

Given how complicated it is to fille a claim, even if I did it myself I would have given up on first rejection. I hope this law expands beyond US.