Reform, while never an easy task, is probably more difficult now than it used to be. Not only is declining trust a problem, belief in governments’ ability and willingness to affect real change is also in decline.
There’s also the tyranny of the election cycle. Often real reform takes much longer than the three-year terms, not to mention assessing whether any given policy decision was effective.
The attitudes of voters are also unpredictable: just ask the prime ministers who proposed the last eight referendums, all of which failed to win popular support.