Yes, custodial also means a reduction in total traffic volume, since you only have to communicate to make a send/receive. Since network surveillance technology is expensive the only concern is that authorities don't attack the users when they are seen using it.

There is plenty of low tech ways to eliminate this problem. Paying forward, a running tab with settlement shortly after the trade...

High tech solutions don't really much exist, but certainly it's conceivable one can have open wifi hotspots attached to servers that the community uses for this purpose, concentrating their resources to have just ONE p2p node in their network and everyone connecting to it to send transactions across.

I'm sure that there is someone thinking towards these ends. Breez is building open source software that can do the aggregation, all that's needed is a mobile client that can interact with the wireless adapter, connect to hotspots tagged with some code that the client recognises as being a bitcoin/LN server and connect and avoid mobile data usage.