Is this really what companies worry about? An insurance (edit: ha, I thought it was a beverage company until I read another comment) company is using a similar colour as our telecommunications company so let's get lawyers involved?
Well, based on a 2017 version of their site in archive.org, their 'pink' is rgb(214, 0, 109) while T-Mobile's current pink is rgb(226, 0, 116). Not the same, but as a graphic designer, I think they'd be visually indistinguishable for most people unless comparing bordering swatches.
But fuck T-Mobile though. Magenta is a primary color in most types of print. That they can somehow stop other people from using it is bullshit.
Apple got away with stealing the name OS9 from Microware so they were not really a position to sue others over similar names without getting their own court testimony from the earlier trial thrown back at them.
The laws are made by the lawmakers (congress, parliaments, etc.)
Justice is there as the supreme/ultimate power to resolve issues between parties. We can't go around smashing heads because "my colour/your colour". When two parties have an issue that cannot be resolved amicably (I don't mean crimes), then Justice gets to say the final word. We live in a civilized world.
Not sure where the line is, but this is a case that's far too close IMO because the shades here change depending on screen type more than they are different from one another.
Amusingly I have 2 LCD monitors here, an acer and a samsung, and when I put Tmobile on the Samsung and Lemonade on the Acer, the colors look functionally identical to the naked eye.