The Fed pays 1.50% interest on reserves; so why are interest rates so low?
There are several issues here:


There are banks offering close to $1.5\%$, some well-known such as Goldman Sachs and American Express 
Most banks currently have excess reserves deposited in the Federal Reserve System which they could use for lending if they wanted to, so they are not missing profitable commercial lending opportunities due to lack of deposits
Many customers are leaving their money in very low interest accounts, possibly through inertia or the attraction of other banking services, and so banks have less incentive to push up interest rates.  If customers want more, they can go for longer-term certificates of deposit yielding over $2\%$
In eras of "normal interest rates", banks took a margin.  For example the old anecdotal 3-6-3 rule for bankers (pay $3\%$ percent interest on deposits, lend money out at $6\%$, and tee off at the golf course at $3$ p.m.) might have been associated with a base prime rate of around $4-5\%$ percent and a default rate of around $1-2\%$.  So with a base rate of $1.5\%$, short-term savings rates should not be expected to be close to this.  Earlier in the cycle when Fed interest on excess reserves rates were $0.25\%$, this margin was not compatible with positive savings rates; only now are banks able to restore their margins