Candidates will anchor on the top number, so you want it to be reasonably accurate.

Also, if most companies give a reasonable range, a company that says "1€ - 1,000,000€" immediately labels itself as a company you don't want to deal with.

In practice, employers try to advertise themselves as high paying, to actually get some decent people. Even basic good stores like to have decent employees.

In most cases, the lowest number will be just below the pay of the worst candidate they are ready to hire and the highest number is the budget for the position. And they will offer you something in between.

The important information is the bottom number. It is useful information for labor sellers to know what type of labor is and is not in demand.

If an occupation or employer advertises $1 as the lower range, then it better allocates labor resources away from that occupation or employer.