Having spent the last 4 years volunteering for a dog rescue charity and having family working in the veterinary world, it is clear that there is so much suffering attributed to no insurance in place for animals. The charity I was volunteering for saw numerous dogs given up to us because their dogs got sick and the owners couldn't afford veterinary treatment as it is so expensive. It was then left to us to take up the fund raising baton for these poor dogs and rehoming them at a time when they needed their families most. From a veterinary point of view, ask any vet if they put animals to sleep because owners could not afford the treatment. I'm sure you know what the answer will be, and many of them probably young animals whose prognosis could be full recovery with the correct care and treatment. Caring veterinary surgeons also hugely lose out on fees where they do treat animals and the owners turn out to have no money. If pet insurance was in place all these scenarios would not exist. There doesn't seem to be a down side to this rule. Compulsory microchipping is coming in to Scotland but that doesn't go quite far enough, the animals need to be insured too. It would take so much pressure off charities too, many of them bursting at the seams and money very tight as animals charities get no subsidies or government funding and rely solely on goodwill.
I have also had first hand experience of using pet insurance, this has got to be an insurance that will guaranteed to be claimed on at some stage in a pet's lifetime. With modern day techniques and the treatments that are available today, they are hugely expensive and can quite often cost thousands of pounds in one go. Very few of us can actually lay our hands on this kind of money to treat our pets, therefore insurance is a must and can also avoid many unnecessary euthanasias.
Another angle is that some veterinary practices (depending on location and client base) struggle financially, due to owners with no money to pay their bills. Compulsory pet insurance would also deter some people from actually owning a pet if they knew the financial implications involved from the start, this may also in turn deter the unlicensed breeder if he/she had to insure the animals they breed and subsequent litters until sold. There will be so may winners on this issue, including insurance companies, but I believe it would lower premiums if every pet owner had to do it. But most importantly the animals themselves will be treated as they deserve to be and not dumped or rehomed because there is something wrong with them and owners cannot cover their treatment. Animals have rights too, they cannot make decisions for themselves and rely on us humans to do right by them and we are continually letting them down.