Fear. It’s that simple. An authoritarian mindset is one predicated on fear. After 9/11, Dick Cheney and George H. W. Bush used fear to drive their policies of restrictive freedoms. They pushed these through so they could amass additional powers and push government money towards their friends. Once these freedoms are gone, they almost never come back. The Republican party has been running on a campaign of fear ever since. Quite honestly, they’ve used fear as their driving force since the '80s. Back then it was fear of the Communists, and then it was fear of 'big government" and then it was fear of immigrants, or “the gays”, or restrictions of the second amendment, or caravans of people coming up from South America. Fear is the only thing that they can run on since they have no actual plans to move our country forward.
The explanation is that those people are selfish. Plain and simple. They want to be able to have abortions and smoke pot themselves, but they don’t want any “others” to receive anything. Republicanism can be explained so easily as “Fuck you, I’ve got mine!”.