The only way to get real change these days is having Congress and the President be the same party, which really is a shame.
Look at the ACA. It's been around long enough now that so far most attempts by the other party have failed to overturn it. But you're right, it's still under attack. So we shall see.
In most cases a country has a professional civil service where political hackery are kept to a minimum and policy making is decided by the ministers and it all filters down.