I can't speak for France specifically but if it's anything like the UK and Ireland then farming families are dis-incentivized to sell land because its costs nothing to hold, and always increases in value. As a farmer you might not even own the land you work on but rent it for the season, and large corporations don't work well with that kind of uncertainty.
NZ used to have subsidies but they got rid of it. Good for them. Fonterra is their big co-op. But with Chinese investment/ownership, most of it is going towards milk powder for export. They posted a loss for the first time last year. Canada has subsidies but different from American. They use a system called Supply Management. They make smaller family farms work better and will survive unlike American dairy. We have more CAFOs and factory farms that are not ecologically and environmentally sustainable in the long run. It’s a mess.