The employer probably gives his employee the "tax-free" money and hopes the employee won't report it on his return. If it is a cash business the employer receives money that he does not report and pays the employee from these funds.
For trusts, the capital gains rate is 20% for the 39.6% tax bracket, 15% for the 25, 28, and 33% tax bracket and zero % for the 15% bracket - according to the USMTG 2016 - paper version.