Whatever the reason, I'm not surprised. For me the surprise would have been if they had completed the work.
Maybe whoever did the undercoat work decided that's enough - and if the bars want a rainbow road, then get out there and paint it yourselves.
Of course, maybe they did complete it - with such inferior paint that by the end of the day it had already worn and washed away.
Which do you think would be likely to come first - immigration deciding to give us all a 50 year visa, and for free or completion of the rainbow road . . . ?