Copper Ethernet standards tend to be specified for over 30 metres, and go (preferably) up to 100m. That’s pretty tricky to do, you need quite thick cable with individually foil shielded pairs to achieve those kind of long distances at 10Gbps. 40 Gbps USB-C on the other hand is recommended to travel over a maximum of a metre or so of cable, with the recommended being 0.8m (2.6ft) of cable or less! Thunderbolt cables that go longer need active driver chips inside the cable in each connector to make the whole thing work.
Then there is the power issue, 10Gbps Ethernet uses significantly more than 1Gbps, so a 40GBase-T switch would be even more power hungry.
The combination of these has meant that basically most people just use fibre if they need more bandwidth.
Ethernet over copper is designed for cable runs of over 300ft and has to be much more forgiving of poor quality cables and connectors. That means for the same level of complexity and power consumption in the transceivers, you're just not going to be able to get as much bandwidth.
Ethernet equipment suitable for 2.5Gb/s and 5Gb/s in consumer equipment (cheap, low power) is now readily available, but there's not enough demand to drive pricing down to parity with 1GbE and completely supplant it. 1GbE is good enough for most consumer use cases, especially given the dearth of multi-Gig WAN connections in the consumer market, the lack of popular use cases that would benefit from slightly faster LAN connections, and the continuing improvements to WiFi.