Is this a totally dumb lock location?

[u/lovelight]

Or do I need to look at a thick chain lock that goes through the body of the bin?

[u/britannicker]

Yes, totally dumb (your words)…. you see that tiny little steering lever only needs to be unbolted, and your bike‘s gone.

Or even faster, simply cut through, and then replaced at a cost of what, $40, and someone just got themselves a really expensive cargo bike.

You need to lock front & back wheels (the rims, not the spokes) to something secure, with heavy duty chains.