An ex pat type, who having moved to France now knows everything about France, French law, French travel, etc. insists it’s is now compulsory and to prove it has shown a jpeg image of a French document, which says who knows what.
There is a world of difference between domestic off-the-shelf travel / repatriation insurance (in the sense of being flown home following say hospitalisation abroad, following an accident abroad or death whilst on a holiday) - which is what we took to be the subject of this thread - and insurance to comply with local laws or requirements for someone living or working abroad on a permanent or semi-permanent basis.
My Travel insurance covers me for death or injury (subject to certain conditions *) abroad whilst on company business. I am then insured separately as well by my company, whilst I am abroad - on company business - too. Both are based on the understanding that I do not live or work abroad on a permanent or semi-permanent basis. Were I to move to live or work long term abroad I wouldn’t be ‘Travelling’ obviously (so that policy would be useless to me) and my employer would need to amend the insurance they bought on my behalf, to recognise that I am now effectively an ex-pat. That is not unusual. No doubt some countries (France might be one, I have no idea) might well demand some sort of insurance or bond of anyone living or working long term in the country, especially if there was no reciprocal agreement. More importantly, anyone living or working overseas without it, might be pretty dumb, especially if it was indeed a local law or requirement.
I’d suggest that your friend obtains proper advice in France, not least as it seems (based on what you’ve told us) to be a French requirement, not a UK one. Though of course, the UK might well demand the same of foreign workers or residents living and working here. As I am not a foreigner in my own country, I have never felt obliged to find out. No doubt my employer’s HR bods know, or at least they should do.
* In essence that it is ‘blue collar’ type work, of the type that I conduct in the UK, along with some other stuff which I forget. Probably something about oil rigs or military action not being covered.
PS Racing abroad is a different matter. Sometimes it is the race organisers - not the host country - that demand that a competitor and or team members have insurance, separate to any that might be arranged by the organisers themselves.