Having worked on a product that actually did this, it's not as easy as it seems. There are many ways of drawing text on the screen.
GDI is the most common, which is part of the windows API. But some applications do their own rendering (including browsers).
Another difficulty, even if you could tap into every draw call, you would also need a way to determine what is visible on the screen and what is covered by something else.
They are resisted because they threaten the status quo of the oligarchs and the useful idiots they are able to convince. In my country, they mostly do it by doing barbecues, concerts during the campaign, giving people in the countryside buckets, umbrellas a bag of rice and bottle of oil, and lots of TV and TikTok propaganda. In the US, religion seems to plays a much bigger role.
But work is ~~9-5~~ 9-6, can't have flexible hours. Everyone knows a busy employee is less likely to get weird ideas like unionizing.
But you can't control and micromanage the ~~slave~~ employee if they aren't physically present at work. And also, we need to keep the employee busy on the 1-2hr commute, see above point.
You mean the poor landlords lose the bread from their mouth and not get paid rent?
Stealing the bread of our poor military complex and police forces? Can't have that.
See point #1
My point is that it's literally a class war between the oligarchs in power and the rest of us.