myrkassi:
Incidentally, why do you think the use of 'tramlines' to describe cane-marks is so widespread? Most writers today have probably never seen an actual tram line (though this may change now the Edinburgh tram is finally running), but the description persists... What would be a more up-to-date simile for them?
Names for various things continue to exist even if the original reason is not there any longer. For example most people call the noise on the telephone a "dial tone" or talk of dialing a telephone. When was the last time you used a telephone that had a dial? In the UK people often call vacuum cleaning "hoovering" even though nowadays Hoover is only one of many brands of vacuum cleaner that they could be using. There are countless other examples.