Much of that depends on what it is you're trucking ... We truck raw milk for a living, and if we parked for 4 days, we would be **** canned in a heart beat. In fact, we've only missed one day since 1949. We park, we're fired, and someone else will step in, in a NY minute. Aside from the huge trucking companies who can't keep drivers in the seat, there's way too much equipment around for the amount of loads to haul.
When trucking was de-regulated in the 80's by the Reagan administration, everyone and their brother jumped into the trucking business, and cut-throat each other to death.. That's what drove trucking rates so low for the independent trucker, and why it's so difficult to make a living in this business. No one has any cash reserves anymore, and only the well established truckers and trucking companies are able to pass the fuel surcharges along to customers. We all pay in the long run.
As far as diesel being more expensive now, (my last drop was over $4.00 a gallon) the only answer I ever get from my supplier is that it's because of all the new "low sulphur" regulations and the cost of removing the sulphur to make a cleaner burning fuel. That's why the newer engines don't puff out all that black smoke anymore.
You're correct in that if ALL the trucks parked, the country would come to a standstill, but it's been tried before, and it'll never work because not enough truckers can/or are able, to stand together.
There's a lot more I can rant and rave about, but I think I best step off my soap box for now.
Kenny