Unless you paid less than 1/3 of that for your ticket, in which case we're giving you just 3x the value of your ticket (yeah, the limit isn't even $1,350, it's 3x the value of your ticket capped at $1,350.)
Nitpick, but it's still not capped. 3x the ticket price, up to $1350, is just the upper limit of what you're automatically entitled to. The airline can offer more. And in this case offering more might have attracted another volunteer costing far less than what the litigation, let alone bad publicity has cost them.
What baffles me is that United didn't even do that. Passengers said the largest offer they heard was in the hundreds.
They offered up to $800 according to all the reports I heard. That same trip taking off today has a list price of $437, so $800 is almost 200% the list price. By law if United could have gotten passengers to Louisville in 2 hours from their arrival time, they would have only been limited to 200% up to $675, so they might have been offering more than what people were entitled to already.