Indeed. Hollywood bears the brunt of responsibility for this. TV and movies portray guns with suppressors as silent assassins. I understand that they want the hero or the villain to have the element of surprise when shooting someone, but it gives viewers a false sense of things. I would hazard to guess that most people don't realize a 'silencer' is not really a silencer.
I have some skepticism that suppressors were used anyways, as there is a long process to buy one. Not only are they a few hundred dollars, but, you have to submit a ton of forms to the BATFE and wait for them to approve you to purchase one. There is an extensive background check for these things and it will be months before you hear anything back. You also have to pay a fee to BATFE of $200 along with your paperwork. So, you'd be down $200 upfront before even buying the suppressor. The actual suppressor itself will be several hundred dollars more. So, you could easily be in $500 for one suppressor. If a suppressor is something you use a lot, then it would be worth it for you.
There certainly are perfectly legal and legitimate reasons to have a suppressor; the aforementioned hearing effects being one of them. So, regular non-criminal people could own them. But, due to the paperwork, background check and expenses, I would imagine they are not common.
A professional or semi-professional criminal may already have the suppressor. It's a good investment for them. Random locals, family members, etc? Probably not, but again, possible. I don't think most people want to go through the complicated, expensive and time-consuming process to obtain one. But, anything is possible.