It is an increasing trend as far as ID is concerned with certain councils refusing to pay the council with the most convenient tip for residents refusing to pay the council running the tip. For example West Berkshire verse the Reading, Wokingham, Bracknell consortium and there is something similar going on just west of Basingstoke. I am sure these are not the only ones with council finances being way they are. The R3 tip (Reading, Wokingham, and Bracknell) is only about 100 yards from Fobney lock (K&A) but displays notices that pedestrians are not allowed AND they expect you to make an online booking giving your full address and provide specified separate ID when you turn up. The barrier is controlled by someone who checks you comply.
However Uckfield tip (Maresfield) is exactly as you say, not checks and I am sure you could walk in.
There seems to me to be an unceasing tendency for councils to encourage fly tipping by making access to their tips difficult.