This is wrong; 1 Gbps Ethernet is 125 MB/s (including headers/trailer and inter-packet gap so you only get ~117 in practice). Infiniband, SATA, and Fibre Channel cheat but Ethernet doesn't.
The 10:1 bits/bytes ratio common in some kinds of equipment is in fact a 5:4 encoding to make it easier to detect bit boundaries and to avoid various electrical problems with the signal.
Modems used to do this too. The 'cheat' is that they report Layer 1 bandwidth, which is a completely useless number to the end user. The bulk of the loss occurs between Layer 1 and Layer 2 (with dribs and drabs for packet headers and so forth)
