If I was the owner of a cat in charter, I would probably want to have a working anemometer. I think it is a safety issue for inexperienced cat sailors. That way the briefing can include things like first reef at 15 knots, 2nd at 20knots, etc. I've actually seen a couple of dismasted charter cats being towed in the last few years, and I've never seen a dismasted mono in 25 years of chartering.

I've sailed plenty of miles on my own monohull, and it is pretty obvious when you need to reef - I haven't ever had working wind instruments for it. It is a lot different on a charter cat, being overpowered feels different and is less obvious. If you are serious about taking care of your fleet, you should make sure you maintain the parts of the boat that can cause the most damage if they fail. I'd say that your steering, standing rigging, anchor tackle, instruments, and engine fall into this category.

Arguments about the skill of charterers are probably not that relevant in this case, there are always going to be less skilled or less familiar captains on board from time to time as long as the business is concerned about asset utilization. You can mitigate the damage with better briefings and better screening, but you still need to make sure that small problems don't become big ones. That's also why I like chart plotters, even though any decent mariner knows they shouldn't be used exclusively. Without them, someone is always going to dead reckon themselves somewhere that they shouldn't be.

Most of the other stuff the OP had happen is pretty standard IMHO, although he was on a bit of a run of bad luck it seems. I would fix most of it by having another beer, and complaining about it later to possibly get some restitution because I'm a cheapskate. Calling the chase boat is a pain and waiting around for them to fix stuff gets old fast.

One time I fed all of our anchor chain overboard in 35 ft of water at CGB, the bitter end wasn't attached. Had to fix that though, BVIYC disapproves of lost anchors. Fortunately we had someone who could freedive 35 ft and find it.