Negative exponents do look odd. I first saw it in RollerCoaster Tycoon like 25 years ago.

Units with negative exponents are non-existent in everyday discourse (articles for the general public, product labels, commercial catalogs, etc.) and even the vast majority of engineering.

It's when you get into science and analysis where you start seeing big compound units and negative exponents. Here are a few examples: https://en.wikipedia.org/wiki/Viscosity#Units , https://en.wikipedia.org/wiki/Gravitational_constant , https://en.wikipedia.org/wiki/Vacuum_permittivity , https://en.wikipedia.org/wiki/Dimensional_analysis

After taking Dimensional Analysis in undergrad I never stopped doing that, quite possibly to the nuisance of everyone around me...

perfectly normal in physics books, maybe not usual in high school, but uni-level books all do this.

Yeah that's the normal way in physics in my experience, certainly from undergrad level up.