The Political Declaration which HMG itself signed up to stated that "The economic partnership should through a Free Trade Agreement ensure no tariffs, fees, charges or quantitative restrictions across all sectors"
Here it is on the HMG website (para 22)
That is a lot more than Canada got. So even if you set aside issues such as proximity the terms and conditions will be more stringent.
If HMG is no longer asking for what it agreed was the goal in October then the question of what changed should more properly be directed at it
Then there is the issue of time. It isn't the EU that insists that everything be sorted in less than a year, it's Johnson. You can't do a Canada deal in that time, it involves negotiating on every tariff. You could maybe -- just maybe -- agree on no tariffs or quotas at all.
But for that, there needs to be terms and conditions. And what might they be? Again, for guidance we turn to the PD, para. 77 and we see that HMG agreed back in October that there should be a level playing field. Again, one has to ask HMG: what changed?
HMG would be on stronger ground if it focused solely on dynamic alignment since as far as I can see the PD called for non-regression, not dynamic alignment. If the negotiating mandate ends up calling for dynamic alignment then HMG might be entitled to ask "what changed"?
But the answer to that question seems obvious. The EU is faced with an untrustworthy negotiating partner that regularly distorts the truth (for example, as outlined above, or with regards to the need under the PD for checks in the Irish Sea).
That means that there is no trust, and without trust you will want to nail as much as possible down now with an eye to ruling out potential misbehaviour in the future. It means strict governance conditions. And so on.
And no 10 has been taken over by a cabal that is utterly committed to divergence in order to steal a competitive march on the EU. As David Frost himself said yesterday. Again, it's on HMG's own website:
"I think looking forward, we are going to have a huge advantage over the EU – the ability to set regulations for new sectors, the new ideas, and new conditions – quicker than the EU can, and based on sound science not fear of the future."
What might he mean by sound science versus a fear of the future? It certainly seems to mean a rejection of the EU's precautionary principle and that raises issues of future conduct that need to be nailed down now. Non-regression won't be sufficient for that.