The first problem is solved by line sensing technology. If there is not power coming in and off of the switch then the inverter will not pump energy back into the system, at least on the ones that are not $12 cheap Chinese junk off of taobao.
And rather than suicide cords they generally have an IEC connector (standard rhombusy shaped computer power connector) on one end and a normal prong on the other.
But you are right that it is dangerous and not recommended to anyone, especially the people that are not smart enough to take the appropriate concerns and considerations into mind before using it.