Sure you could buy $200 shoes for your kid, but they definitely don't need any of that stuff. My kids get plenty of enjoyment from going out for a walk in the woods, which is free, and don't need to go to amusement parks all the time to be entertained.
That's really only a half-truth. Kids cost either A) the net of the salary the parent gave up to stay at home to raise them or B) the price of the daycare so that the parents can continue to work. The presumption that there is a careerless, stay-at-home parent by default is rather quaint, so A is usually a pretty high number. If you live in a particularly populous area, the cost of B will be rather high if you want your kids to be in a well-staffed facility (and who wouldn't want that?) So, there is a specific and considerable cost to having kids, and backend-loading the cost after your earnings have risen is a very attractive proposition, especially for people who are accustomed to a pretty high standard of living, i.e. a roomy house, vacations, driving a "newer" car, etc.
Whlle I agree that CastrTroy's comment was a bit dismissive of the costs of giving up a career for the 2nd parent or the costs of daycare in any developed Metro, there are options to both: 1) Live near family (ie, grandparents) that can care for your kids and assist with transportation 2) Look for in-home daycare or other providers - often nearer, may also work with you on transportation (at one point, our bigger kid got walked back from the bus stop to the provider's daycare).
Trying to get by on one income can be fraught with dangers - losing healtchare (less of an issue now with Obamacare), financial stress of making ends meet, and frustration for the spouse that gave up his/her career. The pernicious fact is that, for larger metros, many families are double income (some with no kids), so real estate and cost of living assumes this. Lower income familes often have 2-4 jobs with one or both parents working 2 jobs to make ends meet.