Why don't higher end amplifiers come with a separate power chassis?

The two most expensive parts of a solid state power amp?

The chassis, and the power supply.

It’s a cost thing. 
 

Now, as I’m about to build a single ended EL34 power amp, I plan to put the power supply in a separate chassis. Mainly for noise isolation. But, separating the two does come with its own challenges, as had been stated above.

@muvluv What does pro gear have to do with anything as far as this topic goes? You make it seem like studio equipment gave birth to high end audio gear? How about, no…

@perkri i wasn’t talking about studio, that is more on the recording side than the playback side. Live concerts and stuff made for the pros eventually made it into the home.it happened many years ago and people forget easily the past. Also car audio helped advance drivers to handle much higher wattage than their home counterparts

Now it's car audio, two entirely different sets of parameters.

I believe early perfectionist audio systems were derived from equipment used in moving picture show houses.  There has been much evolution since.

Yeah.

Car audio is responsible for the ability of speakers to handle highpower.

Right

Small drivers, that can handle higher power came about when higher power solid state amps became a viable option as opposed to the lower powered tube amps that came before that necessitated big, high efficiency drivers in big boxes.

Got nothing to do with car audio…