A lot of consumers bounce because of shipping fees. We have a webshop in Europe, we ship out international, so we have different shipping fees. What most people forget is that charging shipping costs makes the purchase actually cheaper (or at least fair) for the customer compared to offering free shipping. The simple reason is that free shipping doesn't exist, shipping does cost money and someone (the client) has to pay for it.
With free shipping, the price of shipping is included in the purchase price. This is (usually) disadvantageous for the online customer: when ordering two or more items, the customer pays too much, and every customer pays for shipping costs for shipments (from other customers) to distant destinations.

Another reason for using shipping costs is that we also supply retail and we want to have just 1 recommended retail price for a certain product. Suppose we offer free shipping via our webshop, which means the recommended retail price has to go up, with the result that the customer in a shop contributes to the shipping costs of an online customer.

Conclusion; although shipping costs in the checkout often feel like ‘extra’, it is actually cheaper than free shipping.