There is no way a pro can install a GFCI for less than $150 in the ideal case where everything else is up to code. Anything non ideal adds cost. While there isn't much labor, you also have to count the time to get from the last job to yours, and other overhead.
While potentially true, this does not speak to the biggest part of their statement, which was that a predicted small cost project becomes an enormous cost project so regularly to the point that the smaller cost projects are altogether ignored, to the detriment of all.
$150, $1000, all of these are smaller than $15,000. One is a surprise laptop breaking and needing replace. The other is a surprise car purchase and cash purchase.
I'm guessing he was talking about DIY. It's not really that hard, I did it in the 3 circuits in my garage. I'm no pro, although I'm fairly knowledgeable in electronics and electricity.
If you have one guy spending 10 mins in every house on a street, he can probably fit GFCI's to 40 houses in a day. But that's only possible if it's a government/power company scheme. Installation could be even quicker and cheaper if it's installed internal to the electricity meter by the power company, and then you don't even need the homeowner home to do it.
Power companies have an incentive to add GFCI's, because ground leakage costs them real money, and those power flows are only 50% measured by the power meter (depending on the meter design). A 100 milliamp leak at 230 volts costs ~$30/yr or so.
