I don't know what you are all on about. Buying a Shinkansen ticket last time for me was as simple as going to the ticket office, giving the destination, one-way, unreserved seating (was OK for me at the time), then a few taps and I have a ticket.
Only confusing thing may be that the ticket cost is separated into a few components, and this can depend on the specific ticket, seat and train. Once again being "spoiled" by Australia where inclusive pricing is king. (No need to debate the merits of that; that is for another thread).
Of course, last time I was in Japan, I simplified the whole process and saved money by using a Rail Pass. (Not usually ideal if you just have one trip, but so be it).