The unwritten rules are sometimes the same from one side of the world to the other.
One will not need an English lesson to understand this or as we say in French, cours d’anglais à Dijon
There was this client of the agency I worked with some 15 years ago who even though it was a client offered luxurious good as a thank you for the work done. There was this CEO who even though he wanted me as a trainee over the phone, when he faced me he then decided to pay me. There was this Dean who had me as a prospective student and liked my idea of entering a pro-racing young racer programme. Now I offer in ads cours d’anglais à Dijon and it is more straightforward obviously.
Therefore all hard work deserves a reward. From my experience and the one of others I feel it is an unwritten rule.
There are some 5 million unemployed people in France, the economy is crippled and there are possibly far more people earning barely 600 Euros a month. With this in mind it will be not really the etiquette even on a commission based job not to be rewarded, not matter it is contracted or not, it is all a matter of judgement and perspective. It is even worse to privately swear at someone looking to pay his rent and then to publicly hesitate at which luxury watch he is going to wear.
We can now understand the unwritten rules when I give cours d’anglais à Dijon, and I have someone who is more less opened I under there is unwritten rules and I adapt myself.
I say it is tyre-bursting material.