Because making some customers less profitable...

Will make banks want to serve those customers more? I'd say that the economic literacy/idiocy is remarkable but sadly I don't think it is (NYT):

Some who advocate the use of the ID cards question whether the refusal to accept them has less to do with security concerns and more to do with protecting the bottom line. Regulations reining in fees have reduced the profits banks can make from low-income customers, putting the city’s immigrants among the least attractive sources of potential customers.

“If New Yorkers who rely on IDNYC were perceived to be highly profitable customers, the big banks would no doubt change their tune,” said Deyanira Del Río, a co-director of New Economy Project, which works with community groups in New York.