Some sales employees receive bonuses from the manufacturers in addition to their pay on W-2.
This is typical of car salesman whose pay is based on their sales and the dealer issues a W-2. But Ford, Toyota, etc may give a bonus and issue a 1099. I know this is not a prize and cannot go on 1040- line 21 and the person must pay self-employment tax. But they are really not self-employed. Is there a way to handle this other than doing a schedule C?

Stop.

An employee who gets a check directly from the manufacturer DOES put the money on line 21 of the tax return. See IRS pub 525. Look it up under "manufacturer incentive"--the IRS even has posters for break rooms to remind employees that it is NOT schedule C income.

A self-employed person (or the owner) treats it as SE income.