In a discussion on the history of Ethernet and 10BASE5, Stefan Skoglund commented Was 10BASE5 a mistake?
One reason why 10BaseT became possible is Moores law (and the same for the other designs after that.) The designer's chip budget was only good enough for this.
This is an interesting remark that I think is worth expanding on.
Does it take more sophisticated electronics to drive Ethernet over twisted pair than coaxial? If so, is there a way to quantify that? What's the reason for the greater difficulty? What sort of transistor count is needed?
Ethernet ran at ten megabits per second, which was an extremely aggressive speed for the seventies, and even for the eighties. (I remember around 1990, seeing a 286 PC read data faster from a server, over 10Mb Ethernet, than from its own local hard disk – in other words, 1970s Ethernet speed was arguably still overkill in 1990.) Given that RS-232 was running fine over twisted pair since the sixties, presumably whatever difficulty there was, was not so much 'difficulty of communicating over twisted pair' as 'difficulty of communicating over twisted pair and still maintaining signal integrity at ten megabits per second'?