Why is Tom's death considered "typical" in Maycomb in Chapter 25 of To Kill a Mockingbird by Harper Lee?

In Chapter 25 of To Kill a
Mockingbird, Scout notes that Maycomb is curious about Tom Robinson's death
for "about two days."  Tom's death is "typical" to the Maycomb residents because it
is

...typical
of a n--- to cut and run. Typical of a n---'s mentality to have no plan, no thought for
the future, just run blind first chance he saw.  Funny thing, Atticus Finch might've got
him off scot free, but wait---? Hell, no.  You know how they are.  Easy come, easy go.
...  the veneer's mighty thin. N--- always comes out in
'em.

This passage exhibits
the hypocrisy and the rationalization of the residents of Maycomb who attribute a
stereotypical manner to Tom's behavior in trying to escape, in a manner that relieves
their own consciences.

The reader need only recall Tom's
having run when Bob Ewell returned home and saw Mayella hug and kiss him.  After Tom
gives his testimony about this incident at the trial, Atticus asks
him,

"Then you
ran?'

"I sho' did, suh."

"Why
did you run?"

"I was scared,
suh."

"Why were you
scared?"

"Mr. Finch, if you was a n--- like me, you'd be
scared, too."

From these very
words of Tom Robinson, it is clear that he knows that it is certain death if he is
caught with a white woman hugging him, regardless of what he has actually done.  So,
rather than being "typical" in the Jim Crow South that would convict him summarily for a
crime that he has clearly not committed or for a beating to Mayella that he is
physically unable to have given, for Tom running is the only option outside of hanging. 
Tom obviously feels that an appeal on his case is futile; furthermore, he becomes
terrified of the mob that may come again to hang him.  So, he does what any normal
creature on this earth would do:  He tries to escape certain death.  And, because other
Negroes of the South have been in similar frightening circumstances, they, too, run
since they feel that there will be no justice dealt them
either.

That there is no justice for the Negroe is
inadvertently admitted by the Maycomb hypocrites when they say that Atticus may have won
Tom an acquittal, but would Tom wait: "but wait--?  Hell, no."  Upon rethinking this
statement, the townspeople return to Jim Crow in their "Hell, no."  No Negroe can be
allowed to get off from any accusation that he has been with a white woman.  To feel
better about themselves, then, these hypocrites rationalize Tom's escape attempts as the
innateand stereotypical stupidity of a Negroe and nothing more.