> Imagine if police searched houses randomly but "weren't allowed to use what they found unless they got a warrant."
The main remedy for illegal police searches is exclusion of the evidence if, and when, the government attempts to use it in court (and then, usually, only if they attempt to use it against the specific person whose rights were violated by the search, and not always even then [e.g., good faith exception, and other exceptions to the exclusionary rule].)