there is something to be said about the one use rocket particularly for human use.
I dunno. Would you want to a passenger on a new 737 Max that had never been test-flown? I wouldn't.
I'd rather be on the 2nd or 3rd or 5th flight of something where there were already a dozen of the same design that had each made 15 to 20 flights, with zero failures. That's the current situation with Falcon 9 Block 5 boosters.
Note that it was the use-once part of Falcon 9 that failed. Even then it was a completely survivable failure. It deployed the satellites and they might yet be usable. It seems it's not a matter of available fuel and dV but whether the thrust over a complete orbit will be greater than atmospheric drag at the perigee and they can get a net raising of the perigee at all. Ideally, of course, you want to add all the dV instantaneously (or at least over 5 or 10 minutes) at one or more apogees, not thrusting all the way around..
If the upper stage had more than one (smaller?) engine then there might well have been full mission success.
Maybe it's a bit different for things coming back from orbital speed, or higher. Falcon 9 boosters only hit ~6500 km/h, Superheavy 5750 and 5500 km/h on tests 3 and 4 respectively. That's only 4% to 5% of the energy of orbital speed, so no big problem to deal with. The slower Superheavy isn't even bothering with an entry burn before hitting the atmosphere.
There have been 6 Crew Dragon 2 built. The first prototype had a successful Demo-1 flight, but was accidentally destroyed in a ground test of the abort thrusters a few weeks later. The second one was retired after a successful Flight Abort Test. It might well be that it's always sensible to retire them after a launch abort (hopefully after they save the crew!). That should be very unusual.
The remaining 4 built are all still in service, with a total of 13 crewed flights between them, including the one currently docked to ISS on its 5th flight.
There are also 3 cargo Dragon 2s, which have done 10 flights between them (4, 4, and 2)
I feel like the materials are not advanced enough yet to really give me confidence its going to work more then once, and the engineering controls are not fool proof.
Dragon seems to be adequately proven. Starship is certainly still an open question.
I'm sure they can protect it adequately, it's just a question of how much weight they have to add, and how much maintenance between flights.
SpaceX just seems to like to approach the optimum from the "let's prove we didn't do enough" side, not from the "build it like a brick outhouse and then see how much we can safely trim off later" side.