Why is that so? From the 1st list, other than the sutra on
Amitayus which focuses more on other-power (but is also not lacking
in self cultivation instructions), all other sutras were related to
self-power, self cultivation. Seems like you have not read much
yet. 
Second thing is the Mahayana canon is vast and includes all those
scriptures in the Pali canon. Not all of them were listed in the
list. Other than that - the Mahayana canon includes plenty of rich
and sophisticated teachings and methods to enlightenment which are
not found in the other canon.
All teachings are taught according to the conditions and needs of
sentient beings as I mentioned... also depending on what kind of
capacity the person is. If the person is suited to practise the
Shravakayana, then the Buddha will teach him the teachings leading
to self-liberation. If the Buddha sees that someone has the seeds
of practising the Bodhisattvayana, the Buddha teaches the
Bodhisattvayana (i.e Mahayana) teachings, which is to liberate
himself and others and attain Anuttarasamyaksambodhi (the perfect
and complete enlightenment), Buddhahood.
We must know that although the Buddha taught 84000 dharma doors to
enlightenment, all dharmas are ultimately equal in
nature. All teachings are Buddha's convinient means of
conveying the truth to different people.
Subhuti asked, "With what
esoteric implication do you say so?"
"I say so because all dharmas are equal by
nature."
Subhuti asked, "If all dharmas are equal, where are such dharmas as
the stages of Sravakas, Pratyekabuddhas, Bodhisattvas, and Buddhas
established?"
Manjusri answered, "As an illustration, consider the empty space in
the ten directions. People speak of the eastern space, the
southern space, the western space, the northern space, the four
intermediate spaces, the space above, the space below, and so
forth. Such distinctions are spoken of, although the empty space itself is devoid of
distinctions. In like manner, virtuous one, the
various stages are established in the ultimate emptiness of all
things, although the emptiness itself is devoid of
distinctions."
