Why are Airport runway signs only at ground level? How do pilots read them from the flight deck?

I'm asking after the yellow and black signs

They're looking out of the windows and can see them just like the runway markings.

They don't want them high like road signs as they'd be a hazard and subject to jet blast etc.

Thanks . I hadn't considered the wind issue.

Airbanda

And wingtips and propellors etc.

Quartz-1

As others have said they are ground level to ensure wingtip/propellers/podded engines often project beyond the taxiway edges.

They're made big enough to be easy to read, even from an elevated flight.