A market order guarantees you trade and says nothing about the price. A limit order guarantees the price and says nothing about whether you trade at all. Every other order type is a variation on that trade-off.
A limit order that rests in the book adds liquidity rather than taking it, which is why many venues charge less for it, or rebate it. On an illiquid name the saving against crossing the spread easily exceeds the commission.
The cost is being left behind. A limit a cent below the market that never fills during a session that ran ten per cent higher was not a cheap entry, it was no entry, and that missed move is invisible in any trade log.