If you look at the companies you mentioned, they probably pay nbaa average part 91 pay (130k-140 for part 91 large cabin captain northeast job) + a higher of b.s. + worse schedule. Those guys either go to a job like noecorporate has (the higher end of nbaa) or maybe to an airline (especially in these times) or they switch to another company thinking they'll get a little more of one of those parameters.
Per the numbers, those jobs are better than 99% of 135 or regional jobs.
Nowcorporate also mentions that not all those postings are not legit. 100% true.