Why no macroscopic electrostatic electromechanical parts?

Have you calculated the voltages you'd need in order to get the equivalent force or torque? It's much easier to build compact machines of equivalent power based on high currents rather than high voltages.

Making a machine compact basically boils down to being able to concentrate the field adequately. It's easy to concentrate magnetic fields by adding more turns to coils and using iron pole pieces to guide them.

There are analogous structures for electric fields, but a key problem is that air (and other dielectrics) break down under high fields, allowing the electrons to leave the conductors, which ruins everything. Even in a hard vacuum, spontaneous emission puts a limit on how strong a field you can develop.

There is ongoing research into electrostatic machines. A prototype rotary actuator is described by: G. Reitz, B. Butrymowicz, J. Reed, B. Ge and D. C. Ludois, "A switched elastance electrostatic machine constructed from sustainable elements for rotational actuators," 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, 2017, pp. 2389-2395

The described machine operates at 9000 volts and has a liquid dielectric. It produces 2 N-m of torque at stall, but the internal drag torque increases with speed to equal the torque produced at about 1100 RPM. The machine was constructed in a NEMA 42 frame. C-Motive Technologies Inc., is said to be commercializing this technology.

One macroscopic application of electrostatics that's commercially available is Electrostatic Loudspeakers (ESL). These are generally expensive speakers, limited to "audiophile" applications.

More information here: https://en.wikipedia.org/wiki/Electrostatic_loudspeaker