Because the ledger is operated by the issuer, a CBDC can implement rules ordinary cash cannot: expiry dates, per-category spending restrictions, transfer limits, and account-level freezes, all enforced at the ledger rather than at intermediaries.
Deployed and piloted designs differ in how much of that capability is used, and some designs include offline or low-value privacy tiers. The structural point stands regardless of policy: transaction-level visibility and control sit with the state by default rather than by request.