Torque specs are way more complicated than that, regardless if the fastener is SAE or metric.
They are and they’re also not so long as you have hard joints and best practices followed. If your not building a toaster use grade 8, flanged, spiralic or deformed, coarse thread, then the torque range is always the same.
American here - the metric system is far, far superior, logical, and easier to use.
Metric measurements are superior, metric hardware standards are absolutely horrific.
SAE you have one common standard, metric there are a dozen competing ones.
They went for a sloppy fit back in those days. Guess they liked rounded off hex bolt heads, lol.
Coated and flanged fasteners used to have immense variations allowed, good riddance to grade 2, cast and DAC
Sadly pipe thread (and other) fittings have minimal control on the outer diameter so you still have to deal with sloppy fit up.
It's a valid pedantic argument to state that current SAE standards use metric measurements, so saying "SAE" to mean "not metric" is inaccurate. But, we all know what it means and I really can't recall tools being differentiated by any other terms.
You do realize most metric fasteners do not follow SAE standards?
See this chart (available various places online) of some of the metric hardware standards you are forced to commonly use in the US commodity market.
How many do you suppose are SAE?
Metric has a British metric
a German metric and Asian metric and
a French metric which are at the same time sort of comparable/ compatible but also may require completely different tools to install.
This moronic assembly of standards is why metric costs more and is more prone to error in the real world.
If you say choose one and stick with it, first expect to double hardware costs and second which one? Everybody is doing their own thing. Not much different than 120 years ago before SAE existed or the difference between USS AG VRS SAE standards