Make taxable fringe benefits allowable compensation for 401K

Some 401k plans allow for taxable fringe benefits to be included in 401k compensation. The taxable fringe benefits deduction only allows the value to be included in taxable wages but does not allow you to include them as part of 401k compensation. Given that commonly 401k plans can include taxable fringes as compensation, it seems appropriate there would be a toggle to allow/not allow.