In Canada we have: salespersons who sell you items (we used to have salesmen too), cashiers who just work at the cash register and don't assist you in choosing items, managers, and specialty workers such as butchers, bakers, etc. So there isn't a single word that would cover all persons working in a store. I suppose salesperson might be the most common position.
5 There are about 10-12 co-workers who directly report to me in office. It's a private company but of very large size. They are Junior to me in terms of experience and also are below me in Organisation hierarchy. Also I am their manager/boss who is responsible for their annual appraisals in company.
The man who coined the term knowledge workers differentiated them from manual workers. Management guru Peter Drucker coined the term "knowledge worker." In his 1969 book, The Age of Discontinuity, Drucker differentiates knowledge workers from manual workers and insists that new industries will employ mostly knowledge workers.
3 I have been trying to find a word to describe someone who routinely abuses their workers, and perhaps even more than that, scorns them and sees them as inferior. My first guess was despot but I think that is more routinely used within the context of political leaders. I appreciate any feedback.
2 is correct. The democracy is that of multiple workers, so workers is plural. Because of that, the apostrophe applies to the plural form and is therefore after the s. If the democracy was the "property" of a single worker, then it would be that worker's democracy.
In English, there is no single umbrella term systematically used for workers employed by the government (unlike the word "fonctionnaire" in French or the terms "funcionario" and "funcionario público" in Spanish). The various terms that may be used are: public/civil servant, public official, senior/minor [government] official, state employee, government/public worker/employee, functionary. But ...
For example, "We are struggling to replace workers with a high level of firm-specific knowledge." "Firm-specific knowledge" conveys the idea that the knowledge lost is specific to a particular institution (in this case, the company) rather than more general knowledge.
Where I used to work, we called the people who reported to a manager his/her reports. This word does not have any of the negative connotations words like subordinates or underlings carry. Oxford Dictionaries Online lists this as the meaning of the word and also gives an example. Report noun An employee who reports to another employee 'And, I have been a better, more consistent mentor/teacher ...
A Wikipedia article contains skilled, unskilled, semi-skilled, non-skilled and highly-skilled, as well as "Obama Immigration Order to Impact Millions, Includes Provisions for High-Skilled Workers".
1 "Companies" is the subject. There are two companies named as examples (Uber Technologies and DoorDash), each having its own staff. (Presumably they don't share the same collection of workers.) Therefore, the plural "staffs" is correct.