Yes it could be, but not necessarily. Depends on the country and what their laws are. Many countries have regulations of hazardous working environments (including psychological environment) which mandates companies having more than a few employees to facilitate employee representation, even if the company does not have a collective agreement. It's a legal obligation rather than a voluntary union.

Other countries aren't that progressive and only address physical working environments in the law, leaving anything else to the unions.

There's usually some crossover between what the union and safety representatives do.

It would be nice if stuff like this was taught in schools, because there are a lot of misconceptions about it.