The Space Shuttle and the Starship need tiles for termal Protection while reentry.
Why Falcon 9 doesnt need them?
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It is the first stage of Falcon 9 returning from a suborbital flight with much less than orbital speed, about 2.8 km/s and 80 km altitude.
The Space Shuttle returned from a real orbit at much higher speed, about 8 km/s and 400 km high.
2.8 times the speed means 8 times the kinetic energy.
The Falcon 9 booster never goes to orbit, so it is muuuuuuuuuuuch slower. It doesn't even go to space. (I.e. it doesn't cross the Kármán line.) If the Falcon 9 upper stage were to reenter, it would need some form of heat shield.
In fact, the complexities of having the upper stage survive reentry is precisely why SpaceX gave up on the idea of reusing the upper stage.