Let's ignore for a second that you have access to supermarkets and you can buy just about anything you want to eat at any time of day or night. What would happen if you had to feed yourself? Where would you get the primary materials you need to cook a decent meal? After all, tacos don't grow on trees.
You have two options. You might grab a spear and go hunting every time you're hungry. Or you're going to grab a shovel, plant things and raise animals you can eat later.
If you're a hunter, when you get hungry, you're going to start looking for your next meal. You'll hunt from dawn to dusk, hoping to catch game big enough to feed you and your family for the next days or weeks. You don't know when you'll find it or if you'll catch it when you do. It'll be a feast if you do, but it'll be a stressful night if you don't.
If you're a farmer, you start planting now knowing full well you won't get to eat for a while. But once you can harvest, you'll have a steady stream of food coming to your dinner plate. You won't need to worry about going to sleep hungry again.
In both cases, you'll have enough to eat. But only one of them allows for the other. You can't come back empty handed from a hunt and decide to harvest things you haven't planted. But you can go on a hunt while your crops are growing.
Now think of your website's accessibility.
Are you going to wait until issues pile up in your backlog, customers complain and you get slapped with a law suit, before you start fixing things?
Or are you going to plan time for accessibility in each sprint, fixing things as you go, and constantly improving your process so that you never get in a situation where you have to fix things in a rush?
I'd pick farmer every time!
The farmer's approach of planting crops upfront and allowing for a steady stream of food is just like building accessibility into your website and development process from the start. You won't get an overnight accessibility win, just like the crops won't grow overnight either. But you will have a process that, in time, will yield constant and consistent results, while avoiding all the pitfalls.
As a hunter, you're going to be reactive. You'll only go hunting when your stomach is rumbling. Your stomach rumbling is accessibility debt, the unplanned work streams that inevitably pop up when you receive a customer complaint, legal demand, or are forced to fix inaccessible code. You'll be fire-fighting your way through a backlog, constantly playing catch up.
And that's a game I don't want to play.