I've always thought that their choice to post those salary numbers was a bit foolish. Far better to negotiate a low-ball offer for an experienced candidate after selling them on your company during the interview, than to have them avoid interviewing at all because your salary ranges are fixed and low for the industry.
I think you're assuming too much about the data on Glassdoor -- it's not necessarily reliable or precise, especially for positions that require experience. The numbers you'll find there are rough guidelines of average salaries for people who are willing to post to glassdoor. That set is not necessarily representative of software engineers as a whole.
I can say that GlassDoor's data for the jobs I am currently familiar with seems fairly close to my own observations.
$125k/year is what you would give to a decent coder with 3 years of experience. At Rethink, it looks like they want to pay him $80k/year. Some people will take the job just because the company and problem domain looks fun, but not everyone will.
You're living in a dream world.
Please understand that I am not making any statement about whether talented programmers are worth $125K/year - I am simply reporting what I see on the ground.
But it's important to note, I'm not talking about the average developer here. I'm talking about the top 5% who think "reverse a linked list" actually is a warmup question, and can maybe even explain how a binary tree speeds up finding ordered objects.
Besides, where else do you get to work on problems like that? But judging by the other responses on this thread, my idea of fun doesn't seem to be widely shared.