Consider food. You need a job in order to eat. You have to work a lot of hours (maybe with a long commute on top) in order to keep your job, or worse, to make enough money to afford your food and housing. You could save a lot of money and improve your health by cooking your own meals, but that's time consuming. Every minute you spend shopping for groceries or cooking your own food is one less minute you could spend at work. So you live on fast food and a big chunk of your paycheck goes to a fast food restaurant.
Now consider the corporation itself. Its foremost incentive is to provide wealth to its owners. Any incentive to provide value to employees or customers is incidental to that goal, and there are of course ways to avoid doing that. Ideally it's just funneling as much money as possible from the customer to the shareholder.
The poor can't afford to be shareholders. So where is the money going?