Why are bind variables in Toad handled different from SQL*Plus?

I encountered a courious effect when using bind variables in simple SQL-Statements in Toad.
In contrast to SQL*plus where the bind variables are marked as “BIND_SENSITIVE” the same statement is marked as not bind sensitive in Toad. As a result the explain plan is different to the one actually used in the application.
I attached a short example and will be happy if someone can help or comment.

bind_variables in sql-statements.sql (1.91 KB)