To be able to get good photographs consistently, it needs good kit. A typical sports lens would cost in the region of £3000 - £8000, camera another grand. I could understanbd someone being pee'd off if they were unable to recoup their investment in that lot.
That being said, posting full resolution, non-watermarked images is just asking for trouble.
I think the outfits doing the big marathons are certainly charging a heavy premium because of the number of 'tourist' runners who want a high quality momento of the occasion. Us regular runners just get caught in the same trawler net. Smaller racers will often have keen amateurs who will take and sell pics for free or very low cost. I'd buy a pic from them.
Having been injured recently, I've specifically gone to a couple of races to take photographs and have posted them all for free afterwards. Here's some examples if you like to see a few happy runners.