What social trends does Ray Bradbury observe and see as potential problems for the society in "The Pedestrian"?

The message of Ray Bradbury's "The Pedestrian" is a concern that technology desensitizes Americans and causes them to become alienated from others. 

When Leonard Mead walks at night in sneakers so that no one will hear him and call the police,

...it was not unequal to walking through a graveyard where only the faintest glimmers of firefly light appeared in flickers behind the windows. Sudden gray phantoms seemed to manifest upon inner room walls....

Mead...

The message of Ray Bradbury's "The Pedestrian" is a concern that technology desensitizes Americans and causes them to become alienated from others. 

When Leonard Mead walks at night in sneakers so that no one will hear him and call the police,

...it was not unequal to walking through a graveyard where only the faintest glimmers of firefly light appeared in flickers behind the windows. Sudden gray phantoms seemed to manifest upon inner room walls....

Mead experiences an isolation that, as a writer, he finds disturbing. No longer are there people with whom he can converse and exchange ideas, no longer are there people with whom he can share feelings or enjoy company. In addition, he may well be worried about his livelihood, because when the automated police car stops him, Mead is asked what his profession is, and he replies, "I guess you'd call me a writer." The car responds, "No profession," and Mead observes "You might say that" because he has not written in years. People no longer read books or magazines. Instead, they sit in their dimly lit "tomb-like houses" at night, passively watching television that emits a small light that touches their faces. Television entertains them, but "never really touch[es] them" as the written word does because it is the expression of the human experience that unites people to one another rather than isolating them in their lifeless homes. 

Clearly, Bradbury is concerned that, with the distractions of technology, people become desensitized and removed from the enriching human experience contained in the written word.