The solution for you is to only use people who have same day despatch. Better yet, big businesses, so less likely to be affected by the minutiae of life.
After an auction finishes the buyer has 4 days to pay. Which means first that the seller won't know until the end of the auction if they have a sale, and then they don't know when it will be paid for, so they don't have a despatch date.
People do have busy lives, especially those who work and have kids, or are carers. Sellers might be disabled , have one bus to town every other day, hospital appointments, family commitments, sometimes a death in the family, injury or even the car has broken down. An awful lot of businesses are one man bands, many of who have other jobs as well. A lot of people are experiencing a huge drop in orders, so it's a bit unreasonable to expect everyone to hang around waiting for an order and to jump up immediately and hurry to the post office or wait in for a collection.
That's life, and that's why eBay gives sellers the option of a short or long delivery date.
It's the buyer's responsibility to manage their own expectations. A bit pointless paying for, or getting for free, a second class postage option with a 5 day delivery, and then getting annoyed it wasn't posted for 5 days and then takes an age to arrive.
