Extracts from an intriguing (I thought) press release on the Port of Dover website: https://www.doverport.co.uk/about/news/now-is-a-crucial-time-to-invest-in-the-port-of-dov/13610/
"New border infrastructure is needed, identified back in 2018, as a result of Britain leaving the EU and consequent new vehicle processing rules. The Outbound Controls Project will double the capacity of border authority booths to mitigate the increased transaction times caused by lengthier checks.
The EU’s Entry Exit System (EES) is also due to be introduced in May 2022, meaning that all British citizens will have to register a digital identification profile at border control points and undergo a biometric check when entering the Schengen Area under the supervision of a French Police Aux Frontieres (PAF) official. This raises serious and practical challenges that need addressing now.
Under juxtaposed controls, profile registration would in theory have to be done at French border controls in Dover, but the rules for how it will be administered are, as yet, unknown. Juxtaposed controls are the product of the Treaty of Le Touquet, the fundamental purpose of which is to secure the borders of the UK. By mitigating the impact of new lengthier checks and keeping traffic flowing, the project’s successful delivery would maintain the integrity of the Treaty of Le Touquet.
However, if the government does not satisfactorily address the EES, then the future viability of the Treaty of Le Touquet could be at risk, with the consequential degradation of an important element of the UK’s border security. The stakes are high. "
One interpretation is that this goes beyond PoD's so far unsuccessful attempt to get govt funding for the Outbound Controls Project (initially triggered by post-Brexit UK controls on freight) and on into worries about new EU controls on people under EES (had you heard of it - I hadn't?).
Obviously PoD doesn't want any repeat performance of PAF causing A20 tourist traffic to muck-up freight, people sleeping in cars and needing airdrops of fresh water and/or the like. But to raise the spectre of an end to juxtaposition as a less-worse option, with UK inbound people controls returning to the Port, suggests that someone's worried that the OC Project won't be enough.