They don’t need to run failure studies. That basic characterization work is mostly already done for you. Component vendors (should) publish tables of mean time between failure for the components you’re buying that can be used to get a rough estimation with just a few minutes of effort. Typically it’s indexed by temperature, like for caps.

Now, does the bottom of the market actually use those tables? I can’t say for sure. I know one high power headlamp company does this for their LED drivers to balance lifetime with output, but I can’t know for sure what every business does.