Several reasons, but first lets look at what a pizza place does. They are a small, local, business selling a few items that can be made and delivered in a few hours.They have a full time staff that's sole job is to do this. Everything is made to order.
Here is why everything else doesn't do this:
larger business- too many things to have a right on hand to work with therefore...
Warehouses- most things are warehoused, not made to order. These buildings are HUGE, meaning that someone must track down where they are located to have them sent to you.
Staffing- these businesses are not going to have an employee set up just to deliver your item as soon as you ask. A lot of places have delivery schedules, they'll group things and send them all at once. Even less prompt if it is only one person who shows up every Wednesday to deliver everything ordered from the week.
Distance- If the location of your product is in Nevada, USA and you want it in Toronto, Canada; you can't expect it in an hour.... unless teleportation becomes a thing.
I'm sure there are more reasons.