Unionized employees make more than their non-unionized counterparts [0]. Even if the top earners to bottom earners gap shrank in relative terms, in absolute terms both would likely be higher.
[0]: https://www.bls.gov/opub/ted/2025/weekly-earnings-of-nonunio...
If I'm one of many types of service worker, sure I very well might join a union because I'm pretty replaceable and my income has little to do with my individual performance. I'll do better by forcing my employer to collectively bargain on terms that are relatively favorable to me by law.
That doesn't mean that all tech workers should support unions entering their field.