France has the CB network for example which I believe still dominates most credit card transactions although it's declining as more and more cards are not co-branded anymore.
This may be a cultural trait too. Erin Meyer in her "Culture Map" Book mentions this idea that every culture approach persuading others differently from theory-first to examples-first.
There are plenty of dense cities around the world where I'm sure the owners of apartments in the (walkable) center would have enough money to buy a house/McMansion in a nice suburb.
And some do. But plenty don't. And building dense walkable cities with nice public transportation works very well and does not make these cities less attractive as far as I can tell.
I think Paris has a very good pool of scientists/engineers specialized in AI, it's not just a trend. It's probably linked to the engineering schools ecosystem.
It started with AdTech 15 years ago, then Google/Meta opening labs there.
We had an interesting incident where one of our datacenter temperature sensors kept on rising, and operators on site could clearly hear the noise increase of all servers going to max fan speed following a BMC "crash" triggered by a network loop on our IPMI lan.
It took us a while to identify the issue and all systems were running fine, but we had to shut down many racks to avoid the temperature to rise too high.