If people are frequently crossing between crosswalks, there probably aren't enough crosswalks. If they're pressing the buttons but crossing before the light changes, even if the buttons do cause the lights to change eventually they're probably set up incorrectly and make wait times too long.

It took me 18 months of back and forth with my city to get them to fix a particular light. The beg buttons technically worked, but the light is where a major street intersects with a residential street, and all the beg buttons would do initially was make the pedestrian lights turn green the next time the lights changed. Problem was, if it didn't detect a car there it would never trigger a change. What finally got it fixed was me sending the city council an 8 minute video of me waiting for the light to change before a car came along.