Not sure about the US but in many countries you'd still have to report it. For statistical reasons (so that economic indicators can be calculated properly) and to avoid money laundering or terrorism financing rules (the Swiss hotel could be owned by someone on a black list).

(In the US), once you've got a million dollars of clean money in the bank, it's already been taxed and reported by everyone who has an interest in it. I'm sure that someone somewhere would take notice if you suddenly send a million dollars to Switzerland, but there's no reporting requirement here for something like that.

I don't think the US has any obligations on the part of the client for those situations. Banks would have AML (Anti Money Laundering) rules that would require confirming or reporting certain transactions but as an individual you wouldn't have to file any papers yourself.

There is a separate provision[1] that requires the reporting of foreign accounts but I think it's specific to bank and financial accounts. I don't think direct ownership of real estate in a foreign country is required to be reported (as opposed to ownership through a REIT).

[1]: https://www.irs.gov/businesses/small-businesses-self-employe...