The big difference that Americans I've spoken to in the past see as a negative is that it's not just what you say that can be presented against you: your silence can also be used as evidence. That is to say, you aren't compelled to say anything, but if you say nothing, and then later produce an explanation for your actions, a prosecutor can use the fact you didn't mention that before as evidence in court that you may have since invented it.
You can blame
that on the "conventional wisdom" that people only keep quiet if they have something to hide, and that people with nothing to hide should cooperate with police. Only the guilty need fear the police, right?
Our criminal justice system is based on results, not facts. Police aren't required to care who's guilty, they're just here to investigate and gather enough evidence--through whatever means they have--to turn it over to a prosecutor.
The prosecutor's job is not to find and punish the guilty, only to ensure that the person charged goes to prison.
Likewise, a defense attorney's job is to get their client off, regardless of whether they committed the crime.
So it's definitely worth remembering that, when you talk to the police, their primary interest is to gather evidence that can be used against you. That's it. The truth is entirely secondary. The "presumption of innocence" is a joke. It doesn't exist as far as our criminal justice system goes. The only real effect it has on anything is that the word "alleged" is used by journalists.
Having sat in on various court proceedings, I've seen that prosecutors consider a mere
arrest enough to demonstrate your guilt. Even if you were never convicted or even charged, they'll use past arrests, traffic tickets, whatever, to paint you as a menace to society. There simply is no presumption of innocence, as much as we like to claim there is.
That's not to say innocent people go to jail
en masse, or that the guilty always walk free, but you have to remember the role of each person in the process, and use that to guide your behavior. If you're being questioned by police, you are a suspect, end of story. Say nothing without a lawyer.