Limits on Mortgage Eligibility due to Employment

Applying for a property mortgage, an individual with an equities/real estate net worth  higher than the proposed mortgage principal, a stellar credit rating, and yet banks are refusing to provide mortgages.  These loans could be fully secured with the net worth of the equities or existing property.  The banks are demanding a minimum of 2 years of T4 earnings, before providing a mortgage.

It makes no sense that the banking industry has such rigid qualifications for an older clientele that have a spotless track record of 30 plus years.

What is driving this lending criteria?