That sounds more like mob rates than market rates... are people really paying ~20b to have tier 3 stations built?
At least one of the groups involved indicated that even at that sort of rate it had a far higher number of potential customers than people actually wanting to do the hauling.
But it's not an unreasonable rate. If you're hauling in a T-9 or Cutter with 800t cargo [1], you can probably haul about 5000t per hour as a long-term average assuming both loading and unloading of a convenient FC. So at 100k/T that's about 500 MCr/hour ... minus expenses like carrier operations, time needed to split the pay between multiple haulers, getting everyone involved to the right part of the bubble, etc. which are going to mean it rarely hits that sort of theoretical maximum. If the target colony is a long way outside the bubble then the time and Tritium cost of moving the carrier back and forth repeatedly is going to cut into that, too.
There's not a massive amount of room to drop the prices further - especially with a shortage of haulers - before "scan a bunch of Stratum" or "run wing mining missions" becomes a better hourly payout. And "spend 10 hours scanning Stratum so you can pay someone else to spend 15 hours hauling for you" is never going to work out as a sustainable deal.
Sure, it sounds expensive, but it has to be competitive with whatever the most ridiculous PvE money earner currently is...
[1] It's certainly possible that the Panther will lead to a drop in per-tonne prices, longer-term.