According to an article from the JAVMA recently, about 80 percent of pet cats in the US. Not surprisingly, spay/neuter rates were higher among higher income homes and lower where income was lower. The rate approaches 97% in households with incomes over $75,000, but drops to little more than 50% in households with incomes below 35%.
Clearly there is much room for improvement in these numbers in low-income communities. Spaying and neutering doesn't have to be horribly expensive, especially since many veterinarians (myself included) offer it basically as a "loss leader" and lose money on the deal, just to encourage high rates of neutering in the community. Many communities have low-cost spay/neuter clinics, too. The City of Los Angeles provides vouchers when the budget allows, which help to subsidize the cost for city residents.
Spaying and neutering are not difficult or dangerous in most circumstances, and they help to ensure a much longer, healthier life for kitties. They also prevent undesirable behaviors and that nasty tomcat urine odor that will drive your friends away and your family to drink.
I have addressed spaying and neutering here in a previous post, but can't say enough about how critical it is that we do our pets this favor (and society, too).