When exactly, in the US?

There's no tyranny of the majority in Switzerland because of the tools listed above. In other words:

Optional Referendums: Citizens can reject laws passed by the government through petition.
Federalism: Power is decentralized, letting regions make their own decisions.
Open Lists and Panachage: Voters pick individual candidates, not just parties.
People Initiatives: Citizens can propose new laws with enough signatures.

And in another more pragmatic way:

There is no clear majority because we have about 14 referendums every three months, totaling 60 per year at all levels: national, cantonal, and municipal. These cover very specific topics, such as whether to build a statue for X in our municipality, invest in nuclear energy in our state, allow states to define education infrastructure, or veto a specific law. In other words, the topics are so specific that they completely bypass the usual left-right, group-focused politics. You might win one referendum but lose another. No single group ever dominates because the people interested in referendums are always changing.