Boring answer: Same reason we do a lot of stupid things, haha.

“If C is so unsafe and C++ is so unwieldy why does anyone use them?”

Because that’s what they learned, or because that's how the codebase is structured when you get there. When all you have is a bike you’re going to ride that shit everywhere.

You rarely if ever get the chance to start from scratch at work (where most code is written) and your job is to follow the pre-set pattern most of the time unless it becomes completely untenable. Sure, inheritance is worse in pretty much every way, but if everyone you're hiring does it that way, your codebase is built that way, etc, you're going to make the best of it because that's your job.