If Target and Walmart want these subscriptions to be useful, they need to drop the minimum amounts for deliveries. I can order a $5 item on Amazon and get it without paying an extra fee and without being expected to pay a tip because the company is too cheap to pay its own labor costs. If I want a $5 item from Target or Walmart, I also have to purchase a $30+ item that I don't need immediately.

If it isn't practical to do immediate deliveries, that's fine. Just batch the orders and send somebody out to deliver them once you have a full vehicle load or, at the latest, end of day.