You're trying to move goalposts (unsuccessfully) if you pretend that "today" is meaningful in geopolitics. If a country was a colony => invaded after independence + has a currency tied to and manipulated by the former power's currency + has internal powerbases built off the colonial satrap structure and corporate equivalents in oil etc ... it's the height of naivete to think it will "shake it off" a mere 20-30 years later, because some version of democracy was installed.

These are as a category unstable political situations and it is vanishingly few who manage to develop their way out of it. More common is descent into further chaos, with major powers standing by to ensure that it does not disrupt resource extraction.

| post-colonial intervention

I'll ask again. What is stopping these countries today?

Handwavy, vague "post-colonial" whatever isn't a reason, it's an excuse.

The people who control the resources control the armed forces or paramilitary forces.

Plus, if there’s a popular revolt, they are usually motivated by religious, ethnic or ideological factors. Status quo is the interest of the big powers. That tends to bring direct or advisory intervention by western military forces.

I’d suggest spending a few minutes googling, you’ll learn alot.

And as has been demonstrated, popular revolts tend to leave a power vacuum that gets filled by just another abusive regime.