Voluntary funding the way we do everything else. Mutual aid societies (which were killed by govt policy). Insurance cooperatives (also completely distorted by govt). I don't see any reason why we couldn't have voluntary police stations work the same as voluntary fire departments work, my local voluntary fire department works just fine. And having more people on call to provide security with some sort of uber/ride share like coordination should be a fairly easy thing to figure out given all the network tech available today.

Road building & repair could be crowd funded or could still be paid for largely by some amount added to the price of gas if people are willing to pay it. People already buy all sorts of products that contribute a % to different causes. Businesses will often build roads that serve their needs & if they can do so & capture good will from the community in the process they will. In any case, it will all be far cheaper without govt inflation & an army of bureaucrats to pay in the process.