At the bottom a few examples on on how not do do user experience.
Most of them are related to public traffic ticket vending machines, which seem to have a common pattern of having very low usability.
Good UX is possible
There is one example I know that has quite a good user experience, because taking usability into account aspart of the design was done at the start of the project.
This is contrary to most machines: they are built by engineers just taking into account their needs and challenges: build from existing parts, allowing for easier serviceability, aiming for ease of manufacturing.
Dutch GVB did it differently: they hired Dutch design agency [WayBack] Fabrique to design and test the user experience before the whole machine went into production.
This resulted in a machine that combines easy usability, good servicing, and straightforward manufacturing process. In addition, an “extended” version that allows for non-electronic payment was designed and manufactured in the same go.
Fabrique is a strategic design agency, specialised in service design, app development, e-commerce and website design. Discover Fabrique!
(Note I am not affiliated, nor endorsed by Fabrique. I just think they did a very good job)
Here are some pictures of the designed and manufactured machines; the vertical stripes light up the place where the next user interaction takes place: