LOL at all the people getting butthurt over the fluid nature of salaries. Guess what, the value of a salary is very much a personal thing and your own personal circumstances will dictate whether a salary offer good value or not. Someone earning 50K on London sees a very different value to 50K in Glasgow, which is why salaries typically adjust due to living costs. The same concept applies at an individual level. If you have fixed monthly costs then you minimum viable salary demand is going to be a certain margin above the net salary once taxes are removed, otherwise you will soon find yourself bankrupt. If someone has higher fixed monthly costs then it is obvious they will ask for more money, or only apply for jobs that will meet their salary requirement. Hence during the wage negotiation of an interview companies often ask what your salary requirement is, because that is exactly what it is, a requirement form you for a minimum pay level to make the job viable. If you have lower living costs you will have a harder time justifying to the company why you should earn your requested salary. If you have 3K a month in fixed child care costs then you will obviously be negotiating a salary well over 5K per month gross. If the company wants you then they will simply have to pay that. If they can find someone to do an equal job for less money then they can choose to keep looking.
The only things companies can't do is discriminate based on protected status such as gender, sexuality, skin colour or religion. They can;t pay you more because you are a man/gay/hindu etc., but they can certainly pay you more if you ask for more and provide reasons that take into account both your ability, prior salary, and living costs. as long as a company takes steps to remove systematic bias then there is no issue.
And lol at the incels complaining at children. Human race would go extinct pretty soon if it wasn't for parents having kids.