Consider a low-volume exchange-traded security that sometimes sees no trading volume for days on end. Examples of such securities are some bonds, preferred shares, SPACs, and ETFs listed on the NYSE or Nasdaq. Suppose Alice happens to submit a buy limit order at $10 on stock exchange X while Bob submits a sell limit order at $10 on stock exchange Y. Alice and Bob submitted their orders at the same time, at the same price, but on different exchanges. This produces a locked market. Stock exchanges X and Y happen to give traders rebates for adding liquidity but charge fees for removing liquidity. Alice is unwilling to move her order to stock exchange Y because she will then have to pay fees for removing liquidity. Bob is thinking along similar lines.
From my understanding of Regulation NMS, locked markets are not allowed. Do both Alice and Bob have to remove their orders, and later resubmit them with Alice voluntarily decreasing her bid by $0.01 and/or Bob voluntarily increasing his offer by $0.01? What incentivizes them to prevent a locked market when they resubmit their orders?