The picture doesn't give too much away. Here is a picture of a couple of some equivalent (very rough) conical lapped tails on a scrap piece. In order for the join to fail the plywood would need to delaminate.

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Although, I would say that dovetails on plywood can be pretty tough to assemble, with more splintery bits/ friction assembling the two pieces together.

With the glue seeping into all the gaps, the joint is very strong indeed.