This is why when I arrive at a designated pedestrian crossing that has more then one lane without a center pedestrian island I stop back about 1 car length, especially so when I see someone ready, or signalling they will be crossing.

It allows pedestrians, and cars behind me (in other lanes) to see each other, and should allow a little more reaction time for either to stop.

Also people in cars constantly forget kids are just as likely to run across a crosswalk. And at one point those kids might be their kids.