All I have done is defend the importance of typography, and never mentioned piracy or stealing.
Because they're considered important, and definitely take a long time to make. Try making one.
You won't notice many small differences between certain fonts. But that doesn't mean they're unnecessary. As you said, they make a difference when taken together. For screens, there are a number of adjustments and techniques that improve screen readability. Hinting, separate designs, contrast for low dpi and subpixel rendering compatibility, for example. At least some of the optimizations don't work out of the box, but have to be adjusted by designers. That's why it can happen that a font you bought for print media now requires an extra license for websites and apps.
There are plenty of wonderfully readable fonts for the web and apps that are free and sufficient for most projects. If you want something special, I don't think it's wrong to pay for it. Personally, I would prefer more reasonable prices, though.
Maybe if charlatans didn't say with a straight face that a font should be sold on a subscription model they'd sell more? Maybe if it didn't cost as much as a car they'd sell more?
But the differences on the lowercase "t" and "s", uppercase "g", the number 3, and both upper an lowercase "c", are obvious. Helvetica is much more refined.
There are good reasons why well designed typography is expensive. A lot of thought and effort went into designing every line and curve. Even if most people can't consciously appreciate these details, they experience it subconsciously by how the design makes them feel. This is why brand designers are well paid. Anyone can design a logo, but to make a design that transmits a specific feeling, that requires a lot of skill. And typography is a core component of this.