If the insurance carrier only insures the 75 truck fleet and the single owner operator, then being able to recoup in a year from within that pool becomes very important. But the pool for insurance carriers is much larger than 75 or 76 trucks.
Insurance is basically a group of people agreeing to share risks by paying insurance premiums to an insurer. The concept goes back to sailing ships when their cargoes would get destroying when a ship was lost. The merchants found that by dividing their cargoes among several boats, they all shared the risks and protected themselves from total financial ruin. If one of the boats was destroyed, no merchant lost everything. Each stood to lose only a small portion.
When you buy insurance, you join many others who pay money to an insurance company. The insurance company uses the money collected to pay claims that are submitted by those who have purchased insurance. The money is "pooled" and losses and expenses are shared. A critically important aspect is, of course, the members of the pool share similar risk characteristics.
All things being equal (driving and accident record, average miles driven per vehicle, amount of coverage, etc.), the one-truck guy being covered for 20 years presents no more of a risk than the 75-truck fleet, and the insurance carrier doesn't have to worry about whether or not the premiums paid by the one-truck guy will cover his losses, as the losses and expenses are shared by all in the pool. True enough, the bigger the company the more the risk is spread, but insurance carriers don't insure truck companies in a vacuum, they put them all in a larger pool to spread the risk even further. It's exactly the same with individual auto insurance. A large number of individuals constitute the pool as a whole where the premiums for one individual doesn't have to be recouped explicitly to pay a claim.
If an insurance carrier pools all of their insured vehicles into the same pool, and they do, then the rates for individuals and large fleets should not be astonishingly different. The only difference (again, all things being equal) would be the second car discount, so to speak.
That's the second car discount. There's no risk involved. It's not like where 4 tires costs $1000 and the tire dealer goes, :Well, since you're just the one truck and you're only buying 4 tires, for you it's $3000 because it's more risky to sell to you."
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