It was slow and ugly by today's standards but you could still do actual e-commerce well before the web was ready, like buy a train ticket without having to talk to a human.
That's also why you ended up keeping a box in your home that only help in very specific occasions (except if you're taking the train two times a week), and most people would just go to the local post office to use the freely available Minitel when really needed.
I think the worst part was that many of these services were late to embrace internet partly because of the Minitel being a stopgap.
That's because the Internet is an open network where packets pass through multiple ISPs, you don't know what path packets will take, and sniffing packets is easy. Minitel was presumably a mostly closed system managed by a single telco who could keep out bad actors.
The overlay of X.25 Transpac network on IP for payment terminals was cut off 2 weeks ago. [1]
[0] https://wiki.labomedia.org/images/1/19/MinitelMagisClub.pdf
[1] https://twitter.com/jlvuillemin/status/1543841021091528704
That created some household drama... Who spent 200 francs on porn last month ?
I was carefully limiting my usage to free services, or paid services where I could cut (literally) the connection before the 1 or 2 free minutes. Memories...