Hey @Martin,
I unfortunately do not have a great reason for why the event featured image isn’t in the cart; at this time, this is just not something our plugins do.
I will create a ticket for our developers to do this, but doing so is unfortunately an elaborate code customization so it’s not something we can do here in the forums. (https://theeventscalendar.com/knowledgebase/what-support-is-provided-for-license-holders/)
I’m sorry to disappoint, but this is great feedback and I have just created a ticket for our developers to add this to the plugins at some time.
Please let me know what you think and if there is anything else I can try to help with at this time.
Sincerely,
George