I don't know where your information came from, but a lot of it is very wrong. I thought maybe you might be from some other country, but that would mean it's a country that uses dollars that are stronger than US dollars, which I don't think is a thing.

• $50 was the standard set by PlayStation for its biggest games, which N64 couldn't match due to cartridge costs, but this standard carried over to the next generation and continued very, very briefly into the life of the Xbox 360. By 2006, all 360 and PS3 games were $60.
• I bought many PC games on disc back in the day. Call of Duty 2 (not Modern Warfare 2; Call of Duty 2) was $50. You can see here via the wayback machine that a week after its release, Modern Warfare 1 is $50. Here's the PC version of Flight Simulator 2004 and the first Knights of the Old Republic for PC at $50 in December 2003. I remember there was a push to make those $50 games into $60, and the likes of Half-Life 2 and Doom 3 could sort of get away with it back when others couldn't. After buying Call of Duty 2 on disc for $50, I got the $60 version of (original) Prey, because the $60 version came on a DVD instead of several CDs, and installing games from 5 or 6 CDs was a pain that I was willing to pay $10 to not deal with back then (it also came with other collector's edition stuff).
• Steam still does, and always has, taken a percent cut from game sales and not a flat fee. They priced it at 30%, because that was better than brick and mortar retail. These days it starts at 30% and follows a sort of regressive tax system once your game is super successful so that you're not as tempted to leave Steam for other platforms.
• EA pulled their games off of Steam because 30% of a lot of sales is a lot of money, and they wagered they'd stand to do better if they made their own storefront, but after the first couple of years, they stopped trying to make a platform to compete with Steam and really only cared about keeping their own releases there for that 30% cut that they no longer had to pay to someone else.

That wouldn't be the base price; the base price is $70 for the biggest games. I think people are also a bit liberal with labeling games as "incomplete", when really they mean, "this game will have DLC after the fact because it's the best way to make games that take years to make without laying people off". And just to take a brief look along some games in my library, Cyberpunk 2077 would cost a maximum of $100 with DLC, by the time Guilty Gear Strive is sunset (if it runs for 5 years) it will still be shy of $200 in a worst case, and I'm seeing far more games without DLC than with DLC.