I think part of it is that, for the last two years, the economy has steadily been getting better, but investment in new trucks and new employees is not keeping up.
I, too, have sent a lot of LTL loads on flatbeds over the years, and never had a problem- I have a couple of good freight brokers I would call, and a truck would always show up. But in the last couple of years, its been much harder to find one.
I think when things tightend up, during the recession, a bunch of guys lost their trucks to the bank, and quit driving.
And I dont think a huge new influx of owner operators has come in to fill their places.
As an owner operator, which almost all the LTL flatbed drivers I have ever used have been, you need to buy your own truck and trailer, your own insurance, your own gas, get your own licence and medicals. Then, you get jobs, and they send you checks- sometimes next week, sometimes next month, sometimes a couple months down the road, and sometimes never.
Its not a very profitable profession- rates are set by other people, you, as a truck driver dont get to say, Sorry, I need three bucks a mile- and your expenses are all yours, but the income filters thru a bunch of hands.
The companies make money, the individual drivers are often working week to week and month to month.