Following the point about normalisation of dangerous stress, this practice which is linked to attitude is largely at the root of the issue going unnoticed and failing to be addressed.
On an individual level; too often a worker might feel that failing to cope with the workload placed upon them is automatically their failing, that it comes down to personal weakness rather than unreasonable company expectations. Ironically, this feeling in turn is likely to increase stress further as the subject blames themselves rather than factors which may be beyond their control.
Workplaces and management in turn can also be at fault for a number of reasons. Employee experience and skills may be poorly utilised, colleague support may be inadequate, or they may simply be missing the warning signs that a member or members of staff are struggling.