That is a very common misconception about recumbents being nearly invisible. If you can not see a 7 foot long trike flying a flag and with daytime running lights fore and aft, you need a white cane and a seeing eye dog, not a vehicle. I can attest to the fact that drivers give you way more room than I ever got on my road bike (long gone). I had one incident in well over 40K miles riding recumbents for the past two decades. It resulted in minor damage to my trike but none to me. The result would have been exactly the same if I had been riding a road bike. The driver came up behind me hugging the bike lane. It was a sunny Sunday morning and that was the only vehicle visible in either direction on a 4 lane 35 mph road. I'm not sure if he was impaired or distracted but I suspect the former. It is always wise to ride a bike (any kind) like you would a motorcycle. Be aware of things around you and be ready for the unexpected.
I only use the bigger part of the flag when I don't ride with daytime lights. Otherwise it is the smaller flag at the very top.
i can see two downsides to recumbents, the cost and for most people you are going to be slower than on a road bike. In my case, much slower than I was 20 years ago when I regularly rode a regular lightweight road bike. I wouldn't be riding if that were all I had today.