We impeached him twice. He just didn’t get removed.

Because America is a completely corrupt society hiding behind the facade of a first world country. It's an example of how capitalism rewards the shittiest people who have no empathy for others unless they can benefit from them.

Because Republicans vs Democrats has almost reached North Korea vs South Korea status. Republicans want their "democratic" glorious leader and Democrats want profits. And neither care about the people.

no one really liked him being there, even his own party

This is the difference. Trump is still liked by roughly half the country. And the Republican party still fully supports him.

It's a two step process: a majority of the House must vote to impeach, then the Senate has a trial where you need a two-thirds majority to convict and remove them from office. House Democrats actually impeached Trump twice in his first term when they had the majority (once for blackmailing Ukraine, and again after the January 6th attack), but Republicans in the Senate blocked conviction.

Right now, Republicans have the majority in both the House and the Senate, so there's not even a chance of impeachment, much less conviction.

Because it requires political cooperation. And in a society at polarised as theirs there is no chance of that happening with his cult of personality.

The Founders created the impeachment process without consideration for political parties. They naively assumed Congress would act in accordance with the Constitution and standard jurisprudence with no regard for ideology. While it hasn't always been this way, there are really only two parties that matter at the Federal level. The House of Representatives, which is responsible for determining whether a trial is appropriate (similar to a Grand Jury), is controlled by Republicans. They won't even consider holding impeachment hearings, let alone recommend a trial in the Senate. The Senate, also controlled by Republicans, would likely do the same thing they did twice during his first term, which is essentially nothing.

His party members either love him, is too terrified to say otherwise, or is just milking the cow - and they make up the majority of government.

USA is COOKED, sorry to say.

American politicians face zero accountability. It's a time-honored tradition

Trump's presidency is a materialization of Yankee elites panicking. USA is going to lose a hegemony it achieved after USSR collapsed and Trump is making desperate moves trying to stop it. And the ruling class (the billionaires) support it in general.

They cannot.

The republican party is complicit, and supports the evil he does, and more than that, he commands their supporters, so it would be political suicide for them.

Why can't the democrats? The republicans control all 4 parts of government and even if they had control over the senate, they would need 60% of the votes, a number that is unprecedented in recent times.

Fox News and Trump make it so that if members of Congress oppose the president they get death threats and definitely won’t be re-elected. Republicans will let Trump do anything at this point.