Each state has an allowable tint number for the two front windows. Back windows can be as dark as you'd like. Most places that do tinting are required, by law, to tell you if the darkness you chose is legal or not. They have a gage that shows how much light goes through and get the number that way. If it's too dark, they do issue tickets. Some prefer to keep their dark tint and risk another ticket in the long run. I don't care for tickets, or the cost of them, so i go to what is legal in the state i live in. There are legal shades of tint, which vary from county to county in every state. They can't give you a ticket if yours isn't dark enough to cause a problem.
Just because others have it doesn't make it legal in any sense. Being ignorant of the law isn't a way to get out of it either.
Yes, a police officer can ticket anyone with too dark of tint anytime they want. You are breaking the law, and they can ticket you for breaking that law.
If your tint was done professionally you should go back and ask why they didn't inform you it was an illegal shade. You might be able to get them to reinburse you for the ticket if they didn't tell you. When i chose a shade just a bit too dark, the company that did mine informed me right away. In Florida they said they legally had to tell me before they could install it. I then opted for the legal tint up front and put the way dark in the back only.
They sell the darker shades that can't be used up front because you can use the legally on the back windows.