The relevant sub-section is partially quoted below:
(1) Any individual who holds an individual license may operate his or her GMRS stations.
(2) Any individual who holds an individual license may allow his or her immediate family members to operate his or her GMRS station or stations. Immediate family members are the licensee's spouse, children, grandchildren, stepchildren, parents, grandparents, stepparents, brothers, sisters, aunts, uncles, nieces, nephews, and in-laws.
The complete rules part is available here.
The relevant sub-section is partially quoted below:
(a) No amateur station shall transmit:
(5) Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.
(b) An amateur station shall not engage in any form of broadcasting, nor may an amateur station transmit one-way communications except as specifically provided in these rules; nor shall an amateur station engage in any activity related to program production or news gathering for broadcasting purposes, except that communications directly related to the immediate safety of human life or the protection of property may be provided by amateur stations to broadcasters for dissemination to the public where no other means of communication is reasonably available before or at the time of the event.
[This is a very narrow and limited exception, not to be abused for convenience, rationalization or rules-avoidance]
The complete rules part is available here.
The benefits/legalities of day-to-day Oly-Comm operation under Part 95 radio services, as opposed to Part 97, are clear, so the choice was made based upon practical realities.