Companies and insecure people often insist their job titles should be spelt with upper case letters. We are talking here of narcissistic capitals.
This is incorrect grammar — capitals are used at the start of proper nouns.
Bus driver is not a proper noun. Nor is marketing director or chief executive officer.
For that matter neither is president.
A job title can be a proper noun in some cases, that’s another issue.
People who insist writers spell job titles in capital letters think it makes the person look more important. Or because they think some jobs are more important than others and deserve capitals for that reason.
As if ‘head of marketing’ isn’t already impressive enough.
Some people insist on using capitals even when they understand it is bad grammar. As my friend Chris Bell points out they worry that using titles correctly may show the world they are unduly modest.
So they deliberately show the world they are semi-illiterate instead. Give me literate any day.