Actually it’s not that easy and simple as you might think it is with trademarks, domains, similar. For sure a trademark like Zcash does not cover automaticlly everything that might as well contain zcash somehow.
Good example is: amazone versus amazon, both worldwide trademarks for long time used today. No bad faith on either business.
Same would go for zcash if there is for example another trademark for Bizcash, Zcashboxes, Clickzcash (Clickz is a trademark), and so on. Enough the business has indeed as well such trademark and the name is related to their business due a brand, whatever.
It’s most often if the consumer get’s fooled, misslead and so on. IF there is no bad intention, bad faith than it’s most likely NOT a trademark infrigement.
For example if i create another crypto coin naming it: Zcashier there is a good chance it’s an trademark infrigement as it will/could/should misslead consumers.
But if i create a Bank with Clickzcashbank it would not be a trademark infrigment.
I hope you get the idea. IF this would not be like that we would have only a handfull of trademarks as short words/letter combinations just get repeated in words soon or late. Leave alone common used words like cash, bank, invest and so on… The general rule bevor others apply should allways be “are consumers tricked/missleaded/fooled/confused” with a given trademark. IF the answer is NO than in most cases there is no chance it will have success as a trademark infrigment dispute. There are of course some expections.