Distributors and operators want opposite things. Angel gives operators the visibility and leverage to get pricing right, and the technology to keep it there.
Every distributor relationship starts from that tension. It isn't a flaw in any one vendor. Distributors are paid on margin, and restaurants are measured on food cost.
Distributors often open with sharp pricing, and sometimes a signed agreement, to win an account. Once the account is theirs, margin is rebuilt in three ways no single invoice shows. It happens with or without an agreement in place.
Without knowing what others pay for the exact same product, a good price and a bad one look the same on paper. And checking every line of every invoice by hand isn't realistic for a kitchen.