Monero uses enforced privacy by default for all transactions so that no user can accidentally or deliberately be traceable or insecure. Unlike public-by-default mechanisms, this ensures users cannot be scrutinised or penalised by outside actors for using private transactions, leading to non-use of privacy features and therefore loss of privacy altogether.
Monero requires senders to cryptographically generate a one-time address using the receiver's public address. Although all transactions to a given public address end up in the same central cryptocurrency wallet, an outside party can never know whether two transactions have been sent to the same public address.
Source: https://en.m.wikipedia.org/wiki/Monero_(cryptocurrency)