One of them is high delivery cost. Secondly, some Internet users just want to know the total price to pay and want to take some time to think about it before buying.
You can easily activate web push notifications on your eCommerce site and send your users a basket reminder to help them finalize their online purchase.
Or, when you know that shipping costs can be a major obstacle to purchase, you can create a coupon code that will offer the shipping costs to this Internet user. Sometimes, it is more interesting to sell a product by paying the delivery costs, rather than not selling it at all.
Here is a usefull article for eCommerce website owners to maximize your conversions: