From my time at Amazon, I wasn't really a part of these decisions so the following is just my anecdotal perception those businesses and how often teams had things like lunches, team events and hired staff

In general, if the underlying business is profitable or if the product is experimental Amazon will allocate a larger budget to the team

  - Retail has narrow profits and is fairly well established -> Lower budgets
  - AWS is very profitable -> High budget
  - Alexa (while I was there) was growing very fast and was trying crazy initiatives -> High budget

Contrast this to my impression of Google, where it seems like every team has roughly the same perks but only a few make money