Repost from LinkedIn: https://www.linkedin.com/pulse/employee-paying-employer-rudolph-boshoff/
As a consumer I want something in return if I paid for it: when I pay insurance I get peace of mind, when I pay banking fees, I get their service and security, when I pay a car guard I get a warm fuzzy feeling on the inside and when I pay for groceries, I get, well, groceries.
Now show me what I get for the money that goes to the employer before I even see it!
Maybe you would be able to do all the work as a freelance agent that you do for your company, but would you actually get the work? Then there is also the matter of you having to go out there and land the client. You get the service of the employer who brings in the work; the fact that the employer has gone through the effort and expense of registering a company and sustaining it for a couple of years (or a couple of decades) instils trust in potential clients which you as an individual might not have. You pay for this.
The client base
Linking to the previous argument, the employer might already have a big list of names, contact details, references and leads which you have not built up for yourself yet. The company might also be on other companies’ lists where you might not be. You pay for this.
Let’s say you have already managed to overcome the obstacles posed by the first two arguments and you do land a big contract. You will not be paying the employer, but you may or may not get paid less because of the risk factor that the client needs to mitigate because you do not have an enterprise backing you up. Even so, when that big contract runs out you may be without an income for a while. Of course you may have a contingency plan and you may have earned significantly more in the period when there was work in abundance, but the fact remains that you need to work constantly to ensure that you always have work. If you are with an employer, the salary will keep rolling in each month – you are buying “insurance” and you are paying for this.
When working for a company, you do not need to know everything, be skilled at everything or have infinite hours in your day. The acquisition of the skills, man hours and knowledge which will compliment your own can be acquired on your own, but in a company you are paying someone else to do this for you.
We live in a world that necessitates credit – very few people are buying homes and cars with cash. Banks favour those who have a stable, guaranteed income over someone whose income fluctuates and might require a larger deposit from someone who is self-employed. 
It also takes longer to build up a track record. If you have been with the same company for a couple of months, it is already considered a stable job, whereas if you have a more volatile income, you will need to prove your credibility over a longer period of time. There is stability in working for an employer which – you guessed it – you pay for.
This list can of course be extended significantly, but the fact remains that the employer does not just take your money “because the company also needs to make money.” There is a transactional relationship between employer and employee wherein the employer must deliver a certain set of benefits to justify how much they take.
Like with any other type of transaction, each should be judged on its merits to determine whether you get what you are paying for.