Yeah we're hearing stories of the modern culprit being the disposable barbecue none see but suppose to replace the supposed but not seen discarded fag end of yore when there are distinct other possibilities like for instance litter dumped in the environment. Litter potentially in the form of discarded transparent drinks containers more commonly plastic these days but the curved shoulder of forms a lens through which light can be focused to a point and then there's the concave surface on the underside of a pressurised drinks can and am hearing from the Aussie crowd hot engine exhausts, certainly catalysers can be a cause for bush fires.
If we focus intently on one supposed source we tend not to think about other potential sources and we know full well we're rather good at littering the environment we enjoy