(b) Where the state of New York, any of its agencies,
instrumentalities, public corporations (including a public corporation
created pursuant to agreement or compact with another state or Canada)
or political subdivisions sells services or property of a kind
ordinarily sold by private persons it shall be considered a vendor for
purposes of the taxes imposed under the authority of sections twelve
hundred ten, twelve hundred eleven, twelve hundred twelve and twelve
hundred twelve-A and shall be required to collect the taxes imposed by
cities, counties and school districts under the authority of such
sections.