On a normal bike the area where your foot can get caught under the bike is limited to the bit in front of the pedals. That's very bad when it happens but the chances of it happening are very small. On a recumbent that area is pretty much everything forward of your hips and when it goes wrong you're in a feed-forward loop that you can't break out of with a normal physique.
As it happened: hit a speed bump, right leg slipped off the pedel, foot hit the pavement, leg was sucked under the bike at the forward speed of the bike. Ambulance ride, quite a bit of time in the hospital waiting for a slot for the operation, 7 hour operation (pretty long for something as simple as a leg fracture, which turned out to be a lot less simple once things were opened up and accessible because some of the bone fragments were too small to be reliably fixed in place). Almost five years later now and I still have two 30 cm chunks of stainless in there and a large number of screws to hold it all together. Intermittent pain (usually associated with fast temperature changes) and needing to 'warm up' for quite a long time in the morning before I can get around without discomfort.
Avoid recumbents.