Over time phrases and words change their meanings as they adapt to circumstances. Take the phrase “bank robbery”, which has changed its meaning. Once upon a time banks were depositaries of large amounts of cash which was mainly used to pay wages. Because banks held a lot of cash some criminals would rob the bank, often brandishing sawn off shot guns in England and machine guns in the United States. Money was stolen; often the hard earned money of the workers and businesses was robbed and sometimes businesses went bust as a result of bank robberies.
The people who robbed banks became infamous. The robberies became infamous and were sometimes the subject of novels and films and television programmes.
Time passed and things changed. Robbers became easier to catch, cash became harder to wash and spend. Banks started to hold less cash and wages were paid not in cash but by millions of electronic transactions into the bank accounts of people who formerly never had a bank account or even entered a bank in their lives before.
So the banks held millions of ordinary people’s bank accounts instead of much cash. The money in those electronic bank accounts was just as attractive, just as useful and more spendable by the executives of banks if that money could be robbed. So, gradually and with increasing frequency, banks devised a whole series of schemes to rob people of their money. Some were disguised as insurance, others as investments and others were simply manipulated into paying more than they should when they borrowed money while other banks conspired to fix the market in interest rates, stealing a top slice of money from borrowers.
Thus the banks that were robbed became the robbers themselves and the phrase “bank robbery” has now developed a new meaning. Once upon a time people robbed banks. Today banks rob people and bank robbery is most common when banks rob people, rather than when people rob banks.