1st off, practically ANYTHING can be insured. there are insurance policies out on some of the oddest things....
any car driven, 2012 or 1920's, on any public road in any state of the US is REQUIRED by law to be insured. liability only at the minimum.
60's and early 70's vehicles had breaker point ignitions, which need new points every 10k and adjustment every oil change to keep them in the proper dwell range through the entire 10k (or just replace them every oil change, they are CHEAP).
very simple carbs, with little or NOTHING in the way of emissions equipment.
just incredibly simple to work with. beyond the basic hand tools, a 12 volt test light, a multimeter, dwell meter and a timing light covers EVERYTHING.
and you can relatively easily and cheaply switch over to a slightly more modern ignition system, one without breaker points. you'll still be doing 10k tuneups, but there will be less to do and your performance wont be constantly effected by ever changing dwell.
the older vehicles, the muscle car era, they are tinker toys. incredibly simple, IF you understand auto mechanics at all.
newer vehicles, lighter to begin with which is a serious advantage.
fuel injection allows for better mixing of air and fuel, which means a better burn, which means more power with less fuel consumption.
better trannies with more gears that let you get better mpg's too.
and when one the hundreds of parts it has an older car doesnt have does begin to have problems, check engine
light turns on and the computer TELLS you where the problem is.
and lets definetly not forget the brakes.
60's 4 wheel drums was still the thing, and ABS didnt exist. today you'll get 4 wheel disc, which has MUCH more stopping power, and possibly ABS to help avoid an accident (i KNOW ABS saved my bacon at least once, i would of slid out and hit a cop car if the tires had locked up, i was a new driver and i just planted my foot down HARD on the petal in response to everybody being STOPPED just around the corner from me).
and again, lighter cars, which are easier to stop.
its plain and simply STUPID to take an older vehicle and try to use it as a daily driver without upgrading to a more modern and more powerful braking system. you WILL rear end one of those new cars sooner or later when they stop in much less space then you NEED.
personally if i was building a classic car, something like a mid to late 60's mustang, i'd go find a newer (01 at the oldest) truck of the brand i like (chevy) in the junk yards witha v8 in it and completely gut it. motor, tranny, computer to control them, rear axle with its braking system (usually easier to swap out axles then to convert from drums to disc on an OLD axle), EVERYTHING but the body and the frame.
get good power, with better mileage, and all the realiability advantages offered by todays vehicles. and the braking system to make it safe to share the roads with modern vehicles.
bottom line, the older vehicles are easier to maintain for less with less. but they arent as reliable.