Bosses and owners are only interested if there's something in it for them. As in does it increase our output without a proportional increase in costs. The bigger the gap the more social capital I will burn on making that change (including, but not limited to, fucking over my loyal employees by replacing half of them with a machine, or imports).
We would have barely any of those productivity gains if they didn't also lower the cost of labor per item. So this number is a largely hypothetical. And perhaps a little unhealthy to dwell on.
Conversely, though, if minimum wage had kept pace with inflation, we might see higher productivity today because process people would have had the ammunition to push for more and bigger improvements to production and overhead costs. New equipment would be rolled out sooner while prices were still high, making a steeper adoption curve and accelerating R&D expenditure.
Still, it would be better if management did not try to keep 99% of every dollar saved. We could easily see a world where, instead of the $12/hr we should have simply to maintain the spirit of the minimum wage as it was conceived, everybody had Seattle's $15/hr minimum wage and big cities were trying to legislate for $20.