In all of the years that I have been working out relationships with companies to dropship (or be included on The Shippers dropshipping directory list) I have learned a great deal in regards to this question.
The thing I want you to understand first of all (believe it or not) there are tons of companies out there doing a lot of business (off line) that have never even heard of dropshipping. It has been my job to educate them about dropshipping, and explain to them how it can benefit and expand their business. Once they learn of all that can be done online with dropshipping 95% of the business owners I talk to are ready to get a system set up so they can start dropshipping.
So my answer to "those that don't dropship", is simple - they just do not know about it. The other 5% I talk to have limitations as to what the manufacturer will allow them to do with the product, and some companies are so new (and don't have a budget) to get a dropshipping system set in place. There is also a small percentage of companies that are happy with where their business is at, and they just do not want to have to deal with dropshipping side of it.
My suggestion to anyone who runs across a company that does not dropship, is to simply just ask them if they know about dropshipping and what it can do for their business? You might be surprised how many business owners are not familiar with dropshipping products. If you can just educate them about dropshipping, and how it works for Internet businesses, you might score yourself a pretty good supplier.
If you are uncomfortable approaching a business and doing this, feel free to contact us at The Shipper and we will try to establish the relationship for you. We will educate the business about dropshipping and do everything we can to get them to drop ship their products for you.
If you are wanting to find suppliers that are already established as dropshippers, and avoid the hassle altogether then remember The Shipper is offering a FREE 7 day trial (full version) of our premium product sourcing membership and learning center.