Uber, at that time, was "scrappy". Every operating city was a different market with different rules, so Uber was akin to a franchiser that gave their market managers wide leeway to setup whatever business processes are needed to succeed in that market.
Excel is the easiest way for business-oriented people to make numerical decisions, run incentive campaigns, segment riders and drivers, produce reports required by cities, counties, states, etc.
The data teams providing market intelligence to the various markets, of course, knew about servers. But they would not have the time or skill to setup something like this, and the business still had daily data needs. So the laptops it was, for a time.
