I mean what else should they use?

Reality is much mundane and boring: the person writing the web app has no vested interest in the app actually providing a good service for customers. His or her boss doesn’t care either.

It’s simple disinterest: the self-interests of the coders are too far removed from the interests of the customers.

If you’re a solo dev working on a startup and every lost customer is money gone from your pocket, you will pay attention to every little detail.

If you’re a cog in a giant soulless machine, you do the bare minimum and go home.