When you change the tread design on tires, who do you have to inform up and down the supply chain? What do you have to communicate? And what do you have to track differently? You can probably figure out the answers in your head for these questions.
When you decide to, as an example, offer tableside service at McDonald's, what has to change in the business? Well, everything from manpower planning, to store layouts, insurance, tranining, resetting customer expectations, operations and kitchen protocol, OSHA, the website(s), market research, and quality assurance--to name a few. One 'little' service change touches practically every aspect of the business--and totally repositions the customer experience!
What differs with regard to implementation of product and service designs is that product designs usually happen without affecting the way the business operates. New products mean business as usual.
Changes in service, however, require that new connections be forged between department that contributes to the new service delivery model. Each department, role, or person by definition depends on the others to meet service delivery goals as well as customer expectations.
In my opinion, service innovation is more difficult to implement because there are so many interlocking parts to consider.
So, what tools are available to do service innovation work better?
A well thought-out experience map (or encounter/interaction design) shows the details of all the interactions that make up an experience in storyboard form. An experience map helps all of the different 'departments' see the same desired outcome in their own language. Then, each can work in aligned fashion and do the right thing for customers.