Lenore Wilson, 3, was taken by an unrelated couple while her mom was in the hospital (Lenore was later dropped off safe at the police station and the couple was never found):
http://www.websleuths.com/forums/showthread.php?318286-ME-Lenore-Lenny-Wilson-3-Augusta-4-Oct-2016
Dartarian Brooks, 3, was taken by a family friend (found safe):
http://www.websleuths.com/forums/showthread.php?327121-CA-Dartanian-Brooks-3-Oakland-14-Jan-2017
4 Year old Rebecca Lewis was taken from Florida last year by family acquaintance Wild West Hogg and driven on a long road trip, ending up getting caught in Tennessee:
http://www.websleuths.com/forums/showthread.php?318632-FL-Rebecca-Lewis-4-Lakeland-8-October-2016
Last year in NC a 6 year old was taken by a stranger from her front yard (she was found alive, Sex Offender charged with rape):
http://www.websleuths.com/forums/sh...r-kidnapping-rape-of-6yo-girl-Wilmington-2016
Most non-family abductions I can think of they find the child quickly because there is suspicion or some connection-- the person was seen snooping around or knows the family and acted strange around the child or someone saw the child getting abducted, etc. But there are also cases like Diana Alvares where it is clear a non-family member took the child and the child has not been found
Diana's thread:
http://www.websleuths.com/forums/sh...ana-Alvares-9-Fort-Myers-29-May-2016-4/page42
I think the cases where family members harm their children just stick in our memories more (and perhaps theya re mores common? IDK the stats). For sure, the occupants of the home are always the first suspects and my heart drops whenever I read "live-in boyfriend". It seems sadly predictable. I hope against hope that little Mariah is found safe and unharmed.