No, they're not glossing over inflation, because they were able to explain nearly the entire difference in real sales per employee between restaurants during the same time as a function of dwell time.
They are not just looking at an overall increase in sales, misunderstanding sector-specific inflation, and saying it must be dwell time.
It's a good paper! I would encourage reading it. They have specific dwell time data per location, along with sales data, and explain the difference in productivity by looking at differences in productivity between restaurants over the same time period, find that it is determined by changes in dwell time, and then find that the overall mix shift of reduced dwell time explains the overall change in real sales per employee across the sector. Inflation is not the explanation.
They are not just looking at an overall increase in sales, misunderstanding sector-specific inflation, and saying it must be dwell time.
It's a good paper! I would encourage reading it. They have specific dwell time data per location, along with sales data, and explain the difference in productivity by looking at differences in productivity between restaurants over the same time period, find that it is determined by changes in dwell time, and then find that the overall mix shift of reduced dwell time explains the overall change in real sales per employee across the sector. Inflation is not the explanation.