EV is not meant to be used as a proxy for how much a buyer is ‘willing to pay’ the seller but rather to gauge relative cheapness of ‘market value of equity’ given the firm’s level of debt and cash - so that the net cost to the buyer can be better ascertained. Let’s take a look at an example.
Firm A
MVE = 1000, MVD = 0, Cash = 1000
EV = 1000 + 0 - 1000 = 0
Firm B
MVE = 1000, MVD = 1000, Cash = 0
EV = 1000 + 1000 - 0 = 2000
If Firm A is bought at market value (note: cash is theoretically reflected in stock price for publicly traded firms), the buyer pays 1000 to its owners, inherits 0 in debt and has 1000 in cash on hand. Likewise, for Firm B the buyer pays 1000 to its owners, inherits 1000 in debt and has 0 in cash on hand.
Conclusion:
Firm A represents a better buy even though the amount of payout to the owners of each firm is exactly the same. Our assumption is that any differences in non cash operations between the two firms are negligible and are already priced into the stock price. This is all in theory.
In reality however, we know that market anomalies do occur. A firm is usually bought for the non cash operations of an ongoing business. Any excess cash on the books that remains after the purchase is an added incentive for the buyer. If the buyer believes a firm has strong prospects a premium over the stock can be offered taking away some of that cushion of excess cash (and thus, effectively being able to offer up to 2000 with no immediate consequences). Similarly, it may take a while for the market to realize that a heavily indebted firm with no cash reserves deserves to be selling at a discount to the current market price (and thus, being able to offer down to zero with no immediate consequences).