Part of the reason they look so similar is because UCI banned recumbents as soon as they were invented

Take a full-suspension carbon mtb with electric shifting, hydraulic brakes, tubeless tyres etc and compare it to 1895 Singer safety bike. A lot has changed! But of course with more simple designs there aren't that many bits to develop, yet probably every part has changed to some extent since those times.

I don't even know what to say about people scared of a pennyfarthing. I guess they never saw a guy push a motorcycle fast as he can in 3rd gear clutch disengaged, and jump on when the engine fires after he dumps the clutch. (They took away kickers before electric start was reliable)

Weight

Well they have changed a lot. Just the general form of the frame and position of the components hasn‘t. You can see this in a lot of technology (especially mechanical)

Cool video, fellow Albbertan! (And at the end, I thibk you were riding along beside Deerfoot north of 32nd, so fellow Calgarian.)

I'd love to see a breakdown of the true innovations that draw the line from Singer to modern day. Surr materials have improved, but that's incremental. The freewheel and the derailleur are fundamental new innovations. Rim brakes improved over a century, but weren't really new. Disc brakes might qualify as a true innovation. And of course, pneumatuc tires - every few years an attempt to replace them fails once again, because they were an absolute miracle.

I'd also love to see a discussion of what might be, if it weren't for the UCI's punitive rules.