I can’t find any direct evidence now, but I remember hearing (probably in the 80’s) that one of the ideas suggested for assigning Ethernet MAC addresses was to

I can’t find any direct evidence now, but I remember hearing (probably in the 80’s) that one of the ideas suggested for assigning Ethernet MAC addresses was to use dollar bill serial numbers, to avoid having to set up and run a central registry forever. However, it’s technically illegal to destroy currency and the cost of $1 per address would eventually become uneconomic.