The mast majority of legal precedings end with a plea deal.

"Plea guilty to this misdemeanor with a fine and walk out of jail today, or wait in jail for 3 months and fight an uphill court case where people will blindly trust the police and we can fabricate any narrative we want"

"Oh you want to fight and post bail? Okay well for three months we require biweekly drug screenings you pay for, you have a curfew, and if the police can come up with some other bs charge while you're out, we get to tack on bail jumping"

It's not hard to see why people will admit to being guilty while innocent when pleading guilty won't result in jail time