I am putting a meter box on the outside of an 8" thick concrete wall. Last time I did this, years ago, I used lock nuts and plastic bushings on the ends of a short piece of rigid 1 1/2" conduit to go through the wall. After I am through the wall with the cable, I understand I don't need the conduit to get the cable to the breaker box, if the cable is of the jacketed variety. My question is, now days is it acceptable to use PVC conduit to go through the wall, and skip the plastic bushings on the ends?

PVC Sch 40 conduit will work fine. But, bushings are still required with PVC fittings, per Code, as the edges of the fittings may cut into the wire insulation.

Suppose I use a piece of PVC, and glue a 1/2" slice of a coupler to the ends to retain it in place, having first rounded the sharp edges by turning the thing in a lathe (I am a machinist by trade.)... in effect making the PVC conduit to function as the bushing... is that likely to pass muster? Or is it necessary to use the storebought item. It seems if I have to go to all the trouble to thread the thing, I might just as well use rigid anyway.

No. You must use the approved fittings for the installation.

MB is correct, 110.3(B) of the code no longer allows us to be "creative".