Not always. It's better to say that "military grade" means "very specific standards".
That also happens to translate to cheap pretty often, but that's because someone in 1943 wrote the specification for The Standard Tube Sock and ordered 7,500,000,000 pairs to be delivered over the next century. Since it's precisely specified you know exactly how much you can skimp.
Add that to the trillion pages of compatability requirements and you're basically never updating anything.
Like how switching lightbulb brands at a nuclear power plant is hard because you need documentation demonstrating that the plastic in the led won't become a hazard in a radioactive incident.

“Military grade” means cheap as fuck.

Cheap as fuck yes, but also a giant rip-off as well. It isn't military grade without that skimming off as much of that military industrial complex dollar as possible.

The old ones were durable as hell.

“Close enough for government work” is a saying for a reason.