And some of the salaries listed on that site are below band. We also get salaries below band through acquisitions. In those cases, managers aren't really given leeway to get their salaries up to market. We've go a mostly-fixed pool of raises to apportion across our teams. Every year, that's set by executives depending on the company's performance...this past year it was ~4%. Low-level managers can recommend higher for their team, but they need good justification and, at the level of the business unit, raises cannot exceed that value.
Based on what I've seen when extending offers, whereas US citizens sometimes push back on salary or equity, H1-Bs only push back on the INS stuff (they all want EB2s). My guess is a lot of managers will low-ball their offers when they know they can give the candidate an EB2. The more you do this, the more you can increase your headcount or hire more senior developers.