They should make this a specific offence and then put cameras on the toll gates and simply send out fines.
I most often use the M4, M6, M7 and Limerick Tunnel, and by far the worst system in the M7. It often doesn't beep, but the barrier opens no issue, and in other cases it beeps but the barrier stays down.
Since the run up is short, and the barrier is slow to react (database connection maybe?), you really have do drop way below 50kph to ensure that if it doesn't open in time, you can go out the escape road.
If the barrier stays down, you can be right up against it before it opens at 50kph. Then the next car comes along, it opens, and they think you've got through on their tag. I've been car 2 many times, and I'm full sure it's due to a poor system instead of cheating drivers. All you can do is stay so far back, that car 1 has time to realise the problem and get out the escape road.
The LED sign that says "Tag Read, €1.90" is too small, and in the wrong place too. The counter system to make sure the barrier doesn't open for car 2 until car 1 has gone the escape road doesn't work properly either.
It should be a specific offence, where the toll operators is fined thousands, every time the barrier doesn't open on a valid tag, and forces a genuine car to come to a stop with cars coming up fast behind, it's way too dangerous a situation.