Well you've dramatically edited your post since I made my post but I'll take a shot.
Explain how you are not in favour of a minimum wage but having a minimum wage is perfect to maximize profits with productivity at the expense of the worker. If there was no minimum wage, wouldn't it be more profitable for companies and individuals to hire people at a lower than the current minimum wage? What does, "at the expense of the worker" mean specifically? Workers get paid at their agreed upon wage no? What is at their expense?
Businesses lobby to keep it what way? What is a maximum wage?
I agree that what jobs pay is an issue, but has always been and will always be an issue in any dynamic economy, particularly with low or unskilled labour. Someone will always be the lowest paid. So what is the solution? If you artificially increase the minimum wage, especially in great leaps and bounds, all businesses will naturally seek to lower costs, and part of that is reducing labour costs in favour of automating what is essentially menial labour tasks. I gave some examples above but there are plenty others. Take McDonald's for example. You can replace several food servers with several kiosks and a hostess or two, whose sole job is to smile and help customers. Machines don't get sick, don't infect other staff, are never late, don't file lawsuits, don't feel racially discriminated against or have their pc feelings offended, are never surly or flippant with customers etc. Software is fairly simple to create, machines very easy to repair and electronics incredibly reliable these days anyway.
How do you propose to resolve this dilemma?
If there was no minimum wage the power would be more in the hands of the Worker/Unions on what they make, businesses would have to compete to get a workforce as simply paying absolutely nothing isn't going to give you a workforce to supply your demands.
By having a Minimum wage there is no competition between businesses as they can just all stick to this same wage taking all the power from the workers in payment negotiations therefore it gets used as a ''maximum wage''.
Robots are all well and good but your not taking away anything a robot workforce would open up opportunities elsewhere as those robots will still need to be maintained, made designed and operated.
Now when it comes to raising the minimum wage:
Say you have to reduce the amount of workers to pay this extra wage costs via a higher minimum wage the workforce that is working is paid more thus is able to spend more which in turn creates it's own demand, companies are not just going to leave because workers are expensive because there will still be a demand for goods and that demand will have plenty of opportunity for those that supply.
The businesses will have to restructure their pay cycle from top to bottom to cater for this if they intend to keep same or similar profit levels which will essentially close the gap between the highest earners and lowest in said company.
You will find in Countries with High income inequality like America for example the difference from the bottom to top in employee income will be much larger, then other countries with much more income equality that is because of high minimum wage, a company as a whole would rather exist then not and this is basically a by product of that.
At the end of the day an Economy is people, the Economy serves the people just like the people serve the Economy.
Supply and Demand.
(It should be noted that a no minimum wage society will never happen in a Western '' 1st world country'' simply because it adds variables that no government would accept, since it's highly capitalistic and the concept of a government in the first place is socialism the only option that will be hurmonious would be a raise in the minimum wage).