Yes but, picket fencing is much less common that HD drop outs. Getting a LOT of HD drop outs is pretty much to be expected with HD especially in a moving car. AM works well in a car also typically only dropping out under a bridge., at night you can listen to an AM station for hundreds of miles and usually with minimum inteference and drop outs, FM is uaully good for 40-50 miles with no drop outs, HD you can get drop outs within several miles. HD is by far the most susceptible to drop outs and interference which causes the drop outs.
Of course no blame can be laid on GM and their tiny little shark fin antennas, which is basically giving a big "F-U" to broadcast radio regardless of its transmission method.
And if we're going to be honest about AM, it's a much more dire situation than you describe for most Americans. My position is in no way representative of the whole country, but AM is all but impossible for me. At home, it's electronics interference from all the doodads: computers, cell phones, home alarm, satellite DVRs, laptops and tablets, etc. Summer reception is a pain because of the daily thunderstorms that plague the coastal regions. Walking through my neighborhood is much better, as our power lines are underground, but as soon as you leave the community and pull out onto the main highway, the high tension lines fight it out. (I also live across the highway from an AM station running 2.5 kW during the day, which desenses all radios, but I don't count that.)
Nights are great for skywave, as long as you love Fidel Castro because Cuba and Mexico dominate the dial at night. WLS? Never hear it. CKLW? Just a dream. WBBM? Rare as snow in Florida. But Radio Reloj on twenty frequencies? That I can do. Tick. Tick. Tick.
Contrast that to FM, where most of our stations reach 70+ miles from the transmitter and HD — when sitting still — is good for 40, which is big enough to reach the entire markets, despite how spread out everything is. And the stations running higher power are dropout free for those 40+ miles.
To be fair, the one commercial station running high HD power also has night/day processing differences between analog and digital. The analog is "competitive", the digital sounds like someone turned the treble up to 11 but with no processing beyond basic limiting. And then there's the issue I have with cascading codecs, which HD greatly exacerbates. You got your songs on hard drive, encoded in low bitrate mp3, shoved through a lossy digital STL, decoded then re-encoded in the even worse quality HD codec and it sounds like a dog's dinner at the listener's radio.
