Steel belts are usually reserved for the most demanding of applications. Typical examples might include scrap metal reclaiming or recycling plants, or any application involving very high temperatures (250 degrees and above).
Metal belts come in a variety of forms, from the ultra-heavy 'platelink' variety (they look like tank tracks), to the lighter steel mesh (chainmail) and ladder belts. The latter tend to be used more in the catering industry, where their open mesh/links allow air to circulate around the carried product. (often to allow them to cool down after leaving an oven.)
As an example, seaside donut wagons tend to use the lighter grade of mesh belts, along with bakeries (especially pitta breads).