"I" am doing engineering on jet engines in the real world and they don't need that level of accuracy, a claim made by you which is incorrect.
Do you have any evidence to support your claim that the building of modern jet engines requires less accurate measurements than what they were doing in the 1800's? I find a claim like that rather hard to believe and was unable to find any evidence to support or refute it online.
You won't find it on-line because its Commercial-in-Confidence Maintenance data from the manufacturer.
But why would you think that all technical progress depends purely on the ability to measure increasingly long decimal fractions? Since its the example you raised, do you know how the gap between turbine rotor blade tips and the enclosing stator is generally measured in service? Laser? Photon particle accelerator?
No. We normally use feeler gauges, like Henry Ford used to set up the spark plugs on his Model T. Do you know how we ensure that the flying control range of movement is correct on a business aircraft? We use a protractor. Or a ruler.
You really need to consider whether the level of precision you're claiming, in
any field of technology (in the real world) is going to be robust enough to survive erosion, temperature change, contamination, and simply surviving transit from where its made to where its employed.
I don't doubt that there are some engineering technologies that are designed, manufactured and maintained to higher tolerances, but don't quote turbine engine blades as an example when you clearly have no knowledge of the subject or data sources yourself. Perhaps you could provide an example, with sources, from your own field of technical expertise, not just something you read on the internet.