Coffee is an example, but there are plenty of others:

There's a pretty basic problem that a coffee grinder is a motor, the actual grinding surfaces, and the tubes that connect where the beans come from and grounds go to. Maybe add a scale and a little bit of electronics, but still, what does a $1000 grinder have that a $200 doesn't?

Indeed you have to get a lot of things precisely right to get a desired grind particle size distribution and that takes science and study and precision but the end product is still only a few simple parts that meet a specification. The problem is volume and just charging large amounts of money because that's how you attract customers in the "quality" space where having very good taste for quality is itself quite hard.

Coffee grinders are ripe for disruption with a low cost high quality product, but in order to pay for the engineering time to make one you have to have confidence in pretty high volume so picking a price point is hard.

Here's a cheat: use sieves to get the right grind size; then how "good" the grinder is is a matter of only efficiency - the worse the grind the less % is usable and the more coffee wasted. Then you can calculate the best option based on deltas of wasted coffee * coffee cost vs the cost of a better grinder (and maybe expected lifetime, but I assume burrs will wear get worse over time?).