Nice false equivalence. This isn’t even about negotiating, it’s about looking at the website you’re ordering from and actively trying to save money. Domino’s doesn’t hide their deals, they put them under the tab labeled “deals”. If you don’t have the reading comprehension to find those deals, you may need someone else to order for you.
Businesses will sell whatever information you give them permission to sell. Don’t use your main email for rewards accounts or free trials if you’re concerned about having it sold to spammers.