I reserved a Budget Truck for a one-way trip from CA to WA about 9 months in advance. Reserved with the basic insurance from Budget. When I picked up the truck, the manager said he "could not let one of his trucks leave the lot" without the purchase of additional insurance coverage from Budget. Price of $450 but offered to discount it to $398. This would have added 40% to the total cost.
I asked him if I had any choice and was told "no." I paid the fee via credit card. I later called and wrote to Budget complaining about the tactic and got no response. I disputed the charge with Citibank which supported me and reversed the charges. Budget threatened liens and damage to my credit unless I paid.
Then sold the "debt" to a collection agency, Joseph Mann & Creed, a company that is subject of numerous complaints. I suspect the Budget store manager gets a commission on insurance sales and knew that if I tried to rent the last minute from someplace else it would cost me even more.