Flies do have a role in the ecosystem, you know. Kill too many of them and we'd be surrounded by corpses of dead wildlife... We're already worrying about a general shortage of insects...
As an alternative to binning food waste and using plastic bags, I'd suggest that, if you have the space, you just dig a deepish hole and bury the meat based food waste. It's good for the garden. Just the meat based stuff, because that's what the flies that spawn the big maggots are after.
P.S I have to confess that any flies get past me and lay eggs on my cats' left over wet food I wash them away PDQ... There's a limit to my environmental concern.
But I try not to let uneaten wet food linger. Cats have access to the biscuit stuff during the day.