Unfortunately, most service techs have to buy their own hand tools, including the manifold gauges, meters, etc. And because of this, the less qualified often purchase the least expensive items, which means they can never do their jobs well.
And when it comes to manifold gauges; I wouldn’t want any service tech that arrives at my house or business with the standard old 2-knob, 3-hose configuration to work on my air-conditioning or refrigeration system. Why not? Because to do the job properly, the manifold also has to be used to pull a deep vacuum and that can’t be done well using such a tool.