If dealing with rogue parking was that easy, then it wouldn't be a problem. There’s a big difference between knowing the law and correct procedure and managing these problems in an effective and civilised way.
The use and apparent abuse of visitors car spaces is part of the ebb and flow of strata life. Would you ping someone visiting a sick relative for staying a few hours too long? How about an owner who's juggling the departure of an old car after the arrival of a new one? Both of these may be in breach of the by-laws but does it really matter?
The problem arises with regular and persistent rogue parkers who think that fact that they have more cars than they have spaces to accommodate plus the fact that visitors haven't paid to park there, means they have the right to do so.
Then there are the commuters who have “mates” in the building who allow them to park all day while they catch the train to work. You can't fine, warn or tow people who are not subject to the by-laws of the building.
And if members of the executive committee expect some leeway themselves, don’t expect them to be too hot on enforcing the rules.