Also, did anyone call the police to arrest the "Shocker #2" pasted to the bus? Ned certainly didn't tell anyone and he couldn't without possibly revealing that Peter is Spider Man. So, probably the webs just dissolved and he got away. Still, if he got arrested, he'd be the witness to overturn the entire operation, but Toomes tech guy could get him with a drone.
Essentially, the NYC judicial system is just not set up for super villains, yet. Maybe the FBI agents who were on the Ferry might have some sort of evidence to use, but they might be more interested using Toomes as a criminal informant ala Whitey Bulger. There are actually a lot of interesting directions the movies could go if they emphasized the difficulty of vigilantes illegally stopping criminals.
If they introduced a J. Jonah Jameson and Daily Planet, this could be the basic reason he thinks Spider-Man is a menace. He gets in the way of actual police operations and destroys any chance the police have of making a case against these super-criminals. Meanwhile, the audience - because we see it - know that he's the only one who can save the lives of the people these guys put at risk, so he's still a hero even if it hurts law enforcement.