"Not as steppers you can't - nothing like enough bandwidth."

Don't some such systems use constantly spinning mirrors and/or prisms, in conjunction with modulating the laser, to achieve a raster scan?
Just like a CRT has horizontal & vertical scan coils, you have horizontal & vertical scan mirrors (or prisms), with suitable blanking of the laser when it'd be shining "off-screen"
Obviously they'd all need to be synchronised.

I believe that the Texas Instruments digital projection system uses micro-machined mirrors - might be worth a search on the TI website for "DLP"?