I can see your point - but the "contract" was to carry out a task for a price. It seems that happened and you're satisfied with the work - and happy with the price. Not much to argue about.
We've had quite a bit of work done in the last 3 years or so (driveway, garage doors, landscaping, taking trees out, wood flooring, tiling)- it's all been fixed price . . . the labour was irrelevant as long as the job was done in the agreed time scale . . . none of the suppliers said it would be n men for n days - how they worked was up to them.