"...having unlocked phones, pre-paid cards, and even mandatory unlocking is (and has been) the norm since mid-nineties." This is what I am disputing from experience. It is categorically not the norm. Phones are sold locked to contracts. Pay-as-you-go is possibly marginally more popular, but the phones are subsidised and locked. Yes they can be unlocked and normally for a fee. The French law you allude to is out of date and falls foul of Directive 2005/29/EC (see the entry on Belgium in the wiki link). There is no law in France or most other EC territories as illustrated in your link.
EDIT: Funnily enough one of my parents, a resident of France, has had an iPhone 3G, 3Gs, 4s and 5s on contract with Orange. Not one was sold unlocked with their contract.
Phones sold, in France on pay-as-you-go (forfait bloqué) and monthly deals (forfait) come with a locked phone. Yes, they may be unlocked at any time (http://assistance.orange.fr/desimlocker-votre-mobile-2839.ph... and http://assistance.sfr.fr/mobile_forfait/mobile/desimlocker-m...), much like the can in the UK (http://service.o2.co.uk/IQ/SRVS/CGI-BIN/WEBCGI.EXE?New,Kb=Co...) or indeed in Germany (http://www.t-mobile.de/sim-lock-entsperren/0,20638,23789-_,0...). The end user must still pay the remainder of their contract even if they choose to use another provider. SIM only deals; either 30 day, PAYG or 12 month contracts, are commonplace. Suggesting that in anyway they are the norm is incorrect.
EDIT: Funnily enough one of my parents, a resident of France, has had an iPhone 3G, 3Gs, 4s and 5s on contract with Orange. Not one was sold unlocked with their contract.