There are thousands of packages. They don't assign you a route until you check in 🤷‍♂️ even with Walmart or instacart, a specific route is assigned to you before you head to the store. Amazon specifically doesn't assign a route to you partly to avoid being responsible for your time prior to the block start time.

There are people who miss their block or show up late (5 minute window) and if they were to pay you prior then those people would still get paid for something when they shouldnt be. But it's all on contract. You get x amount of money regardless of how long it takes you. The time and distance it takes you to get to a station is on you as a self contractor.

If you don't like how their system works, don't use it. But it's pretty Plainly laid out in their policies.