Lewis cited this as one of the "small" things that the company used to do as a partnership that came to an end under their corporate ownership.
It seems he made a general statement about public companies then made his case by focusing on a specific industry. Banking has been especially dishonest lately but have private banking companies been less dishonest? I think the pressures to be dishonest are there regardless of whether you manage a private or a public company.
There had been a trend, haven’t seen anything about this lately, of moving public companies private. In fact I read stories 10 years or so ago warning about a coming shortage of public company stock.
I personally have worked at both public and private companies and I highly prefer privates.