I think it's more complicated than that, bustabit might quailfy for an exemption/exception, they don't store much data to begin with and (I think) they aren't targeting nationals of any specific EU/EEA countries. But IANAL, maybe EU courts must make enough rulings for things to clarify.
Thank you for the post.
There might be a way websites serving EU citizens would not need to comply with GDPR but as of yet I have not seen cases and as you rightly pointed out it might be more complicated than the manner in which I put it. Some clarity on legality would be appreciated by users who might read this post.
From what I recall, any website that stores any information on EU citizens that reside inside the EU must comply. So for example an EU citizen holding a passport from any EU country but living outside the EU would not be covered but the hundreds of millions living within the EU member states are covered.
https://en.wikipedia.org/wiki/General_Data_Protection_Regulation
https://gdpr.eu/checklist/
https://www.csoonline.com/article/3202771/general-data-protection-regulation-gdpr-requirements-deadlines-and-facts.html
And this is the golden rule so far as I could remember: "Any company that stores or processes personal information about EU citizens within EU states must comply with the GDPR, even if they do not have a business presence within the EU"
As excellent as both Bustadice and Bustabit are and as highly in regard as the community hold its owner, complying with GDPR and adding a cookie notification would only enhance credibility to those not familiar with the background of the websites. Adding those would not take anything away from the website or the user experience so maybe it is worth the OP thinking about.