You do of course realise that doping France is a criminal offence.
Why are the French not competing for GT wins? It is a criminal offence to dope! Simples.
So they, IMO, do enough to stay under the radar, be competitive for stages and top 10s. It would appear that ASO are not bothered about a French TdF winner, neither are the French government because sure as *** they would sanction a rider to 'go for it'. I guess a certain country got the go ahead to do it with their pro team. They just won their 3rd Tdf with a Brit rider. Knighthoods were handed out to the 1st winner and team manager.
The TdF for France is a massive tourist advertisement If i remember correctly the French government gives ASO money towards the TdF. The more foreign riders that win it the more tourists flock to France, is my thinking behind the non French winner. It is always about money.
But this idea that the French don't dope is for the birds. They do it but not enough to be competitive with super doped teams.