Because senators don't want to look into your bedroom and it's obvious. We all know this. A story most people remark with gladness on is that Al Capone was sentenced to 11 years in jail for tax evasion over $215k. AFAIK, there is no minimum amount above which you're eligible for the 5 years. In addition, most states have a sales tax evasion penalty (California can put you in jail for a year). Now, many Americans commit sales tax evasion all the time fairly purposefully when they buy online.

People love the fact that Al Capone was put away, but they don't want to be put away for their miserable $200 unreported either. They give the government the overarching power and then trust it to use it right.

That's what the Senators in your Bedroom argument misses. Everyone knows the senators don't want to look in your bedroom. Everyone knows that the senators want to look in the terrorists' bedroom. The only worry is that some rogue senator will look in your bedroom knowing you're innocent but Americans trust in the rule of law and believe that won't happen. The Senators are on your side. They're the good guys. The Child Pornographers are on the other side. They're the bad guys.

Now, I support E2E encryption. But it's obvious to me why this argument won't convince anyone. The real argument is more subtle and involves the erosion of civil liberties and the deleterious effect that will have on the American Republic. I think enough Americans generally understand this that they will protect it.