They’re largely doing it because as a contractor having to go back and forth between the construction site and a trailer / office to access items like drawings

They’re largely doing it because as a contractor having to go back and forth between the construction site and a trailer / office to access items like drawings in on-prem software is a PITA and leads to errors and rework. It also carries enormous risk of anything happens to the device with the data on it. Employee that just got fired drops laptop with project plans in an oil drum on the way out? Yeah that happens. All of the big players in construction project management are cloud and mobile and anyone that tried to pitch anything different would be at a substantial disadvantage for all but the smallest contractors.