Tieflings in earlier versions of D&D were depicted as trending towards evil and reveling in destruction (like a certain bard in BG2). This was attributed to their fiendish ancestry, and their inability to resist (or willingness to follow) their innate evil predispositions. Their more recent depiction as occupational thieves and organized criminals is a "politically correct" revision of them as victims of non Tiefling prejudice, which forces them to live in the high crime areas of Humanoid cities, corrupted by non Tiefling criminal influence. Larian's writers have promoted them to "noble outcasts" and oh so fashionable victims. As part of this overhaul, they relentlessly smear Druids of all "races" and ethnicities except Arron and Halsin, because the Druids, too, are supposedly victimizing the noble and suffering Tieflings.

THAT IS why Tiefling children are unkillable. Larian's writers want you to like and support Tieflings, and hate and kill their enemies. They likely have an extended storyline coming up involving Tieflings that continues after the player reaches Baldur's Gate. The discussions I've seen on the internet don't even mention that the Tiefs have made enemies of the Druids who saved them from slaughter by goblinoids and humanoids by stealing compulsively and repeatedly from their saviors.

Goblins, though given more dept and complexity in BG3 than in earlier D&D based CRPGs, are still ugly, filthy, irredeemably evil subjects for mass killing to keep their rapidly multiplying hordes from increasing out of control. This is the first CRPG I've player that actually includes (very cute but still maliciously evil) Goblin children, who are nevertheless remarkably scarce in the camp and the Shattered Sanctum relative to the supposedly rodentlike fecundity of their elders.

I'm a professional biologist, a volunteer wildlife rehabber (like Nettie, with whom I had an instant bond, particularly since Blue Jays are my great favorites among North American birds). I'm also a hobbyist non venomous snake keeper who coexists with wild American Black Bears, Canadian Lynx, Bobcats, and Coywolves, and other potentially dangerous wildlife, none of which have any remaining equivalents in the wild in Larian's Germany because rhey were systematically exterminated centuries ago. This means that their writers' perspective on 'real world' Wolves, bears, etc is based on what they see safely confined in zoos or in entertainment mefia, NOT on their wild counterparts! Vipers do exist in Germany, in the fotm of the fairly rare Adder (Viper berus). However, Germany, despite the genocides of the Third Reich, still has many Roma, while they are very scarce to nonexistent in the neighborhoods of most of this thread's readers and commenters.

"Reality" is a product of surroundings based experience, and subjective perception!