The particular reaction from parent taking away the devise may be more important cause here. I've seen this play out: some mom making repeated attempts to take away the ipad with the sad face looking like she was strangling the poor kid. No confidence, no desire to engage with the toddler, make eye contact. It's sad really, the parent behaving like this can't be giving much thought to parenting anyway and such meltdown is much more a cry for attention.