Just to have a tow truck show up for an 18-wheeler in the States hasn't been less than $700 in my memory. And that's before the work begins. Most big companies have some form of road assistance, and that's for any breakdown. Rare to get underway again in less than two hours. I've waited as long as five for just a tire change.
Tow trucks are big expensive vehicles. Serious overhead.
FWIW, if I'm sitting more than hour at customer or consigned, the clock starts at $125/HR. Doesn't happen often, but I've sat as long as 27-hours. Let's remember that this is commercial not private. Things are different.
(Or, why I wouldn't want an RV requiring big truck recovery equipment).