30,000 events over 20 years is not a lot. Do you know how many millions of operations there were in those 20 years? That is around four per day. Definitely not a lot. There are tens of thousands of operations a day across the county., ATL alone is over 2000 a day. Also, a runway incursion does not have to have another plane involved. It could be at 3 in the morning with one plane taxiing and crossed the wrong runway with no other aircraft moving. That would still be a runway incursion.