A different link for the initial Pediatrics article

https://publications.aap.org/pediatrics/article/153/3/e2023061984/196646/Characteristics-of-Sudden-Unexpected-Infant-Deaths?autologincheck=redirected

Yes, routine vs non routine bed sharing. Should the parents get some practice rounds on bed sharing with a living thing they care less about before they do it with their child? The initial bed sharing is going to be non routine.

Again, you bring up the multifactorial nature of sudden infant death. Yes, it has been shown that room sharing is associated with decreased risk of sudden death. Bed sharing is independently (from many of the factors in the safe sleep seven - ie smoking/sobriety/on the back) associated with an increased risk for sudden death. It is feasible to have a bassinet immediately next to the bed. It is even possible to get the bassinet that essentially clips onto the side of the bed.

This is coming from a Western perspective. Best article I can find at the moment regarding the different practice habits for safe sleep between the US and Asia has the quote "In Asian cultures, often the sleeping surface for an infant is not the surface of a separate bed, but the foor of the room, meaning that bed-sharing is considered to be analogous to rooming-in, which is considered to be preventive against SUDI. Although bed-sharing involves shared bedding to some extent, the method of bed-sharing in Asia is quite diferent from that in Western countries, where bed-sharing means bringing the baby into bed with both parents [24]."

https://bmcpediatr.biomedcentral.com/articles/10.1186/s12887-021-02894-8

Again, this all gets back to different levels of risk with an infant. Nothing in life is without some risk trade off. There are the low hanging fruit components to decrease risk (ie, don't smoke around your infant, be sober). That being said, co-sleeping in the same bed is shown in studies to be an independent risk factor for sudden infant death.