$2k for one week of travel expenses was based on 5 nights of hotel at $150/night ($750), 5 days of rental car at $200, gas for the car at $40, roundtrip flight at $500, travel to/from home airport at $60, parking at home airport at $50, and 6 days of meals @ $55/day ($330). Grand total $1930 plus taxes and tips.
When my company rented out the convention space in the Hard Rock Hotel plus rooms for 50-100ish employees, the room rates were still $150+/night. Granted that was the same week as CES, but I don't think hotel costs scale down that much unless one is willing to sacrifice location or something else.
The other things should be scalable a bit with tradeoffs. That said, I wouldn't be too keen on going on a week long work trip where I can't leave the hotel, must eat every meal at the hotel with my colleagues, and don't have any way to get around. To me, that means a successful event would have to budget for people expensing at least some of their own meals and for people expensing at least a few taxis/ubers.
Again, my experience with big company gatherings is tied to CES which is its own beast, but in the case of CES my company pretty much left everyone up to their own devices in terms of getting to/from the hotel and for most meals. Hotel rooms were also individually expensed (but out of a reserved block of rooms). My company was obsessive about expenses and the cost of CES, so I imagine if there were a cheaper way to do it, we would have been doing it that way instead.