I fully agree that Virgin (& indeed all airlines) should proactively inform you of your right to compensation - but they deliberately don't to avoid a huge bill. A PA announcement saying "Everyone this delayed flight is now entitles to €300 - go to
www.virginatlantic.co.uk to claim it" could lead to a bill of €135000 for Virgin if 450 passengers on a LGW/MAN config 747 all claimed.
The airlines clearly use the loophole that the ground staff would have told you about EU261 had you asked. Most people are just happy to have got to their destination & just want to get to their hotel / home asap. This was certainly the case when I was on VS75 that arrived 4hrs late at 7pm local time in Orlando (so most passengers thought it was midnight & they had been up early / with tired children etc). There was no hot food on this flight for PE or Y due to a return to Manchester to fix a fault (food had started to cook and had to be binned) - vouchers for hot food at Orlando airport were offered by ground staff on arrival, but they got few takers due to the delay / tired passengers.
I claimed EU261 and Virgin paid up in about 3 weeks - this was when you had to print + fill in a form and send it to an address in Luton. Good to see that Virgin have really streamlined the process and are now paying out within a few days.
As to the mention above of claiming for a delay caused by a lightning strike - can't see them paying on this one. Anything weather related is beyond the reasonable control of an airline.