Why does the Last Traded Price (LTP) not match the bids and offers in the market depth?

The quotes shown in the market depth are based on the buyers and sellers, whereas the Last traded price (LTP) is updated once a trade takes place.  Therefore, the LTP does not fluctuate to match the bids and offers, though the fluctuations are seen in the market depth. Clients can check the Last Traded time (LTT) for the latest trade time.