Is avoiding prohibitions out of fear of people, not God, considered minor shirk, and what about performing prayers solely to please one's parents?

Abandoning sin falls into four categories: First, abandoning it out of fear of Allah. This is rewarded and a good deed is recorded for it. Second, abandoning it to show off to people and seek their praise. This may lead to sin. Third, abandoning it out of shyness from people. There is no sin in this, and one may be rewarded for it if it is accompanied by a legitimate intention, such as preserving the status of dawah (inviting to Islam). Fourth, abandoning it out of a lack of desire for it, neither out of fear of Allah nor for the sake of creation. This earns no reward and incurs no sin. Acts of worship are only accepted under two conditions: sincere intention for Allah, and compliance with the Sharia (definition). So, whoever prays only out of fear of their parents, without the intention of seeking Allah's pleasure, their prayer is not accepted.