The mural in the underpass – showing people from the past – was repainted a couple of years ago and covered with an anti graffiti covering.
That does not stop graffiti but it does make grafitti a little easier to remove.
A google search shows that this particular graffiti statement “Question Everything” predates most of the rest of the mural.
Euripides (Greek playwright, c. 480-406 BC) said “Question everything. Learn something. Answer nothing.”