Why are required reserves so trivially low?
The world changed in 2008, and commercial banks substantially increased their reserves held at the central banks in many countries including the US, mainly because they did not want to lend to each other in the unsecured interbank market

At that point, required reserves failed as a policy measure for fine-tuning money markets in many countries, since it amounted to pushing on a piece of string; the Bank of England removed them entirely in 2009.  Several central banks moved to alternative instruments, including:


quantitative easing 
interest on excess reserves (in the US they were small and positive but some cases such as Euroland the equivalent could be negative)
bank capital ratios, as a solvency regulation