I am based in Sweden, I have done 17 sits:
I am now a bit drooling about a 5-month sit on Réunion (French island in the Indian Ocean) but I don’t think I will do that 
In all of those places, my European Health Insurance Card is good for medical expenses.
Waouh! Go to La Réunion it is an amazing beautiful island. It is a chance if you work remotly.
How many POs have cancelled your petsitting without compensating you ?
Only one has cancelled. That was the day after the sit was confirmed, so no big deal.
On the sit in Italy, no pet sitting was needed because the owners decided to take the dogs with them (one of the dogs needed injections). But the HO let me stay at their apartment anyway.
None of us — including neither you nor I — have data. And your hearing anecdotally isn’t necessary to tell that some hosts don’t find sitters. It’s obvious from various posts and through just using the site and seeing context clues.
Of course, you can hope, but judging from THS’s various decisions, they’re not likely to do as you hope. They do have all the data. And there’s no need for a company to share such with their users.
That’s all well and good but these days you can’t get onto a Cruise Ship without evidence of travel insurance that includes medical evacuation. We sometimes use ships to travel between locations as it’s easier and more pleasant. BTW we never fly Economy- never have and never will…. been flying turning left since 1980.