I sold to Walmart for 4 years. In the beginning we believed we were lucky to become vendors. Then we realized how much stress they created. Every single year they would short pay our invoices. We would have to submit a claim with Walmart accounting. This process was completely and utterly time consuming. But the worst of it, they wouldn't pay the invoices owed until a year later. It's hard to float a $100,000 short p…
They then intentionally delay milestone payments about 3/4 of the way though the project, watch the company fold(since that's the highest-burn part of the project) and then re-hire 2/3rds of the existing staff who are now out of a job to finish the title.
It doesn't produce the highest quality games but I'm sure it earns them a bit more money.