The lower bound of ~45k might be attributed to the German salary cutoff of the EU Blue Card (long term visa for skilled workers) at €45,552 [1]. When I was offered my first dev job (and first job in Germany), it was exactly this number.
Unfortunately, these too-low lower bands are negatively impacting the job market for everyone. Companies have no incentive to increase their pay if they know they'll always find someone willing to take the minimum band for a couple of years just to get into the country.
IMHO, the minimum salary required for a blue card/work visa, in any country not just Germany, should be slightly above what the median wage is for locals in similar positions as the point of skilled immigration should be to uplift the market, otherwise it's just another wage suppression scheme with extra steps that only benefits the employers at the expense of the workforce which now have less bargaining power.
Who cares what software company's in Germany want? They don't want to compete for talent and valuable projects, so talent will want to leave and the company actually wants to cease to be. If you are in Germany, you leave for swiss, Luxembourg, Netherlands for certain improvement, sv for the paygap, to chzekia, Estonia or Poland for a startup. Germany is a old folks home going broke, not a country to start a software development.
Around my area (Central Cali) H1B's are generally hired at a higher rate only because the position couldnt be filled by a 'local', especially for public positions. The FAANG's managed to abuse the system enough that rules have changed to something more like what you envision. At least from the hiring practices Im party to.
For a business in Australia to sponsor a visa for an international hire, they have to prove that they were more qualified than a local applicant and pay them more. I'm not sure if that's always followed, but it certainly made it very hard for myself to get a job.
Now I'm a permanent resident after being with my Australian partner for over a decade, self employed and running my own company.
IMHO, the minimum salary required for a blue card/work visa, in any country not just Germany, should be slightly above what the median wage is for locals in similar positions as the point of skilled immigration should be to uplift the market, otherwise it's just another wage suppression scheme with extra steps that only benefits the employers at the expense of the workforce which now have less bargaining power.