Knackered before first launch
The shuttles were designed in the mid-late 1960s and built in the early 1970s with a configuration dictated by pentagon demands that knobbled it and made it so dangerous the military decided to not use it much.
For 2 decades it was a solution looking for a problem - a combination of Haulage truck to build a space station that almost never happened and what was originally supposed to be a small lightweight astronaut return vehicle leading on from the Dyna-soar project. Most of the missions were "makework" to justify the thing's existance, but ended up wearing the birds out before their designed mission could be completed (it would have been better to hanger them)
Ironically even before the turnaround cost blowouts caused by the aftermath of the Challenger debacle (much more inspection for what was already a creaky old design) expendable launchers were cheaper for most missions. Shuttle was supposed to be substantially CHEAPER than expendables but turned out to be "anything but".
The reason Buran never flew a second time wasn't due to costs, it was becuase the russians didn't want the bad publicity of having one break with people onboard.
Thankfully private schemes aren't beholden to senatorial pork (yeah right) and wouldn't do anything as stupid as building critical solid fuel booster rockets so far from base that they needed to be shipped in kitset form and bolted together before launch...
The shuttles - for all their gloriousness - were enormous white elephants. Now they're no longer holding things back perhaps there will be better progress in launcher technology.