Yup, that's reasonable too.

But like, that makes it a lumpy salary and not a bonus if it's an entitlement without a reasonable low floor. Are there union contracts that actually dictate it like that?

Setting aside for a moment the understandable and reasonable belief that owners will try to fuck labor, a mandated cost divorced from the broader company financial performance metrics, sounds like a way to ensure bankruptcy. Even without this tariff nonsense there are real and honest cases where costs can skyrocket and a company has to adjust and that really does can little to nothing for the bonus pool (or other labor cost) without incurring a lot of financial risk.

Again, not an argument against unions, 100% support organized labor, but at some point math is math.