I remember those #10 juice can accumulators. A major difference in those applications is that the overall vacuum demand was fairly low. Vacuum was used mainly to power short term functions like moving ventilating flaps and locking doors. There was no continuous demand like the wipers.

This was also in the early era of emission control systems. The small accumulator was needed to prevent a temporary/sudden drop in vacuum which could affect the emission control system.

Rusty