re: 401(k) discrimination testing

I don't understand how a company doesn't pass non discrimination testing. Is nobody besides the highly compensated employees participating in the plan? Is the plan not following their own vesting and participation rules? If there is a long wait to start participating, the company needs to change their plan policy and just auto enroll everyone at 3% when they are eligible and put it into a low risk default fund. That way you get people to participatte and hopefully avoid the non discrimination testing.