Insurance wasn't regulated back in the day, though. The regulation is a relatively new thing going back 2-3 decades. Prior to that, selling insurance, pensions, etc was pretty much unregulated or very lightly regulated, hence all the mis-selling claims re endowments, mortgages, pensions, etc.
I started work in the early 80s in a small accountancy practice. The owners ran "side line" businesses, one being an insurance agency, another being a hire purchase company, alongside being a building society branch. We weren't qualified regulated under the Financial Services Act as it didn't exist back then. I didn't personally get involved with HP or general insurance, but I certainly did a few applications for clients wanting pensions or mortgages, and that was without any qualifications nor experience/training in those areas.
It all changed, if I remember rightly around the late 80s. I remember a mad scramble by the partners of the firm to create lots of files for all the clients we'd done work for in the areas of insurance, pensions, mortgages, HP, etc., to make up files showing "know your client", risk assessments, due diligence, etc so that we'd be compliant when the new rules/law came into force.
So, depends how far you go back, but I suspect when travel agents tried to sell travel insurance, there weren't the laws/rules surrounding it as there are today. It was probably because the Financial Services Act came into force, that travel agents/travel companies stopped doing it because they'd have need all their staff involved to be trained and qualified and the commissions they'd have made wouldn't have justified that cost.