1. Customers can't find what they're looking for.
Poor Web site navigation is a subject in and of itself, but for commerce sites it causes nearly 30 percent of all abandoned carts, according to The Yankee Group. Whether you use a tab system, like Amazon.com, or a directory, like Walmart.com, two things should govern your site's navigationâ€"consistency and purpose.
Consistent design throughout your site makes it easier for your customers to find their way: Users can always click on product images for more information. Buttons use a consistent colour. Links are always underlined. If your site is simple for users to understand, they will happily keep moving toward the checkout. Walmart.com's recent redesign came under fire by industry critics for being too boring. However, the changes made the site cleaner, simpler, and easier for shoppers to master.
Your site's navigational structure should also be determined by what your customers intend to buy. eToys does a smart job of reflecting how shoppers think when buying specific toys. Customers can find toys by age, type, gender, and interest. With so many toys to choose from, eToys ensures customers find exactly what they're looking for.
Major don'ts
Don't underestimate the search box. For example, iQVC discovered that more than 50 percent of its customers used the search box to navigate its site. To make it even more effective, the company overhauled its search function so visitors can search by colour, brand, ring size, and price.
You have missed the most important point. Users abandon shopping trolleys - because they can! It's no problem. There's no comeback. They aren't real trolleys. No one gets hurt.
Why consider it as a problem? It's no different from window shopping. More people can do it and more will walk away because they had no real intention of buying in the first place.
You have lots of good advice about how to encourage potentiall buyers to purchase, all of it valid. But where's the problem? In a different paradigm, people will behave differently. Just because they put stuff in an internet shopping cart, ther is no implication that they ever intended to buy. Many will be just testing the system to see what happens, to try to understand how it works.
It may be that with the most perfect system, most visitors will never buy, so expending effort to improve the percentage is not cost effective.
My point is, understand the motivation of users and fix problems that really exist.