I don’t fully understand either what the Backstop is nor what the “problem” with it is.
I “think” the DUP are concerned that it could last forever, or certainly long enough, for NI to gradually morph itself into Eire (Apologies Sloop, I know you don’t like it, but it’s written on the front of your Eire/Irish/EU Passport ) (and I know that I haven’t put the Axcent over the E ! it’s too difficult on this forum !)
However, I have just listened to Jeremy Vine whilst having lunch and there was an NI business lady who was incredibly enthusiastic that the Backstop would boost the NI economy four-fold and turn NI into the Singapore and Hong Kong of Europe.
Basically “tariff free” trade between GBR and the EU could take place via NI. Rather than goods going directly Sheffield - Munich or vice versa and being subject to WTO tariffs, they would go via Belfast, tariff free.
Now I know this doesn’t answer your question, and it doesn’t provide any clarity to me neither, but perhaps over the next day or so, interviews like this might shed some light on the subject.
Who needs Brain Teasers when we’ve got Brexit !