I didn’t read the whole thread but poltroon pretty much summed it up.
I spend ~15 years providing emergency and non emergency transport to UC Davis and other area equine hospitals. I only did show hauling for the h/j barn that I used to manage because I knew the trainer, the clients, and most of the horses and big h/j shows are a drop off/pick up days later kind of thing. Hanging out at shows waiting for horses is not my idea of a good time, OTOH, hanging out at vet hospitals when it’s not my horse that’s the patient, is very interesting.
The insurance was expensive, but so was I 
I believe I provided a good service, and so did my clients. It allowed trainers to not have to take horses to the vets because they could count to me to look after the horse, and I helped the onesey owners understand vetspeak etc.
I enjoyed doing it 90% of the time, it paid for my truck and trailer. I stopped doing it when life changed. I miss doing it, a lot sometimes. Would I haul a horse for someone else now that I’m not carrying commercial insurance? No way. I mean yeah, I’ll haul one of my BFF’s horse to the vet for her, or something like that. I’ll haul the horse, she’ll farm sit for me a few months later, that’s just trading favors. But outside of that, no. I still get calls sometimes, and when it’s a colic late at night or something, it IS hard to say “I’m sorry, I don’t do that anymore”, but other people’s horses are NOT my responsibility, and it IS my responsibility not to expose myself to that kind of liability. In all the years, the hundreds of thousand of miles, I never once had a problem where I needed the insurance I spent all that money on, but when you don’t have insurance is when you damn sure WILL need it.
That’s my take on it, hope that helps.
