Of the public companies I've worked at, all had insider trading policies and it was stressed repeatedly there will be legal repercussions. You are allowed to trade yes, but only during open trading windows, typically following an earnings report.
I think most public companies make sure that upcoming earnings data and such is only released to people on a "need to know" basis. It doesn't seem reasonable that thousands of employees would have access to it.
Plenty of data is shared internally with rank and file. Netflix for example openly shares (internally) subscriber numbers, which is a critical piece looked at during the earnings report.
