Upper Limit. Hiring you at $3,000 a month will increase my income by $3,000. No reason to hire you. Below $3,000 and I can make money. But ~1/3 employees are

Upper Limit. Hiring you at $3,000 a month will increase my income by $3,000. No reason to hire you. Below $3,000 and I can make money. But ~1/3 employees are lazy and I can't fire them. So I have build in some safety margin for the bad employee's. So I can pay you $2,000 a month and on average I'll break even. No thanks. So I can pay you $1,500 a month, I'll make $500.