All manner of electronic devices have been made virtually waterproof for marine use for over 50 years.
One accidental slip and your $600 phone just doubled in price. (!?)
Its not like I am asking for a flying car.
Your example is not valid. Marine-grade electronics are very expensive, compared to consumer-grade electronics with the same function. And, because of the high design costs are updated far less frequently.
In the cell phone world, you can get a waterproof case for most high-end phones for less than $100. This fulfills your desire for far less money than a marine-grade phone would cost.
If you don't like that, you are free to continue using a land line (which have been around far longer than cell phones, but are not waterproof either).