When does paint cost more than carpet?

Answer: When the NSW tax-payer is footing the bill.
Dragon's teeth to guard school zones
Some quotes from the article:
"THE NSW Government will spend $13 million on new line markings near every one of the state's 10,000 school zones."

"NSW has 3200 schools - but thousands more school zones because many schools have several road boundaries."

"The dragon's teeth markings would be painted on each side of the road for 35 metres at the start of each school zone."

"The program - which has the backing of road safety advocate Ron Delezio - would start this week."

So we have 3200 schools but 10,000 school zone entry points. Government is going to spend $13 million painting marks for 35 metres at the start of each zone. Let's do some calcs.
$13,000,000 for 3200 schools gives $4060 per school.
$13,000,000 for 10,000 zones gives $1300 per zone.
$1300 for a 35 metre length gives $37 per metre. I believe you can buy carpet cheaper than that. You surely can if you buy 350,000 metres of the stuff.

"Mr Daley said flashing lights had been installed in 293 school zones as part of a $46.5 million program that would eventually cover 566 school zones."
That is $82155 per school for flashing lights. Perhaps the painted road is not so expensive after all.