I haven't ridden a bike in a very long time. Did you know the Wright brothers made a living owning and operating a bike shop? I'm not joking that's fact.
I used to ride my bicycle everywhere, it was my preferred mode of transport. Where I live now it seems half the people behind the wheel aren't paying attention to what they are doing, so I don't really want to be the squishy bag of bones in any undesired encounter with the idiots.
Yeah, we don't have shoulders where I live in most areas and it's hilly and curvy, so not very safe to go bike riding. It's why my road bike is hooked up to a trainer in the basement.
You don't need shoulders, you just need the majority of motorists to be paying attention to driving rather than their phones. I used to ride on roads with 60mph speed limits and no shoulder - the road was wide enough that I could stay mostly out of the way and every once in a while a car would need to slow down until it could pass me.
A shoulder doesn't actually help much when motorists are so distracted they drift back and forth right across the road.
Our roads can't fit a vehicle on each side AND a cyclist. Someone has to die if they all appear over the curvy hill and around the bend all at once. We also have the Amish here and people forget to go slow around the bends in case the horse and buggy is up ahead. You don't want to be in the other lane with a semi truck coming around that curve right at you.
... which goes back to the problem of people not paying attention. Where I used to live you could ride on most roads and not feel like you were taking your life in your hands. If people are paying attention you don't need endless places to run off the road; if people aren't paying attention then having a bit of extra road the other side of a strip of paint isn't really much of a solution.
Even paying attention won't help when you're driving on a hilly curve going 45MPH.