Your delivery fee comes from the price set on the pickup point/transporter record matched to your delivery day and zip/route — different routes or locations can charge different amounts. It can come out to $0 in a few situations even when a fee is normally charged:

• The pickup point/transporter has "Charge only one fee per day of pickup?" turned on (the default for new ones) and you already have another checkout on the same delivery date at the same pickup point — the second order isn't charged delivery again.
• An applied coupon grants free delivery for a module in your cart, which zeroes the fee for that day's delivery (see the Coupons Q&As).
• For a Catering proposal or a Subscription, a staff member can manually waive delivery fees for that specific order from the admin side (a "Disable Delivery Fees" setting) — this zeroes the fee regardless of the pickup point's normal price.

Outside of those cases, the fee shown is simply what that route/location is configured to charge.