How should the law define "reasonable explanation?" In the US that kind of thing is litigated, which small companies can't afford.
Such protections exist for employees, involve lots of lawyers and complexity, and sometimes screw companies and sometimes screw employees and sometimes screw both (though they do also fill an important need). But the economic cost of compliance and management of these rules is quite high, and there are a lot more employees than software developers by several orders of magnitude.
A law could be written so it only applies to larger companies. Those companies both have greater leverage/power over consumers and small businesses (making the regulation more important), and have more resources to handle the overhead. I believe some existing regulations in the US already have an annual revenue threshold before they kick in.
Such protections exist for employees, involve lots of lawyers and complexity, and sometimes screw companies and sometimes screw employees and sometimes screw both (though they do also fill an important need). But the economic cost of compliance and management of these rules is quite high, and there are a lot more employees than software developers by several orders of magnitude.