Like your Photos WD, at least there is a bull in the field well places above the notice, warning of his presence. All to often these warnings are meaningless, further information on breed type and stockmanship information informing that a a risk assessment has been carried out would help being placed alongside such a notice.
An obvious safety protocol in the second with the highland cattle would be electric fence sections of the lane that the cattle congregate on, where if puts the walker at a terrain disadvantage to avoid approaching the cattle. Personally in this instance I would think the risk assessment low.
Bulls a bit more obvious in your 3rd photo. Herford bull, breed traditionally placid running with a mixture of crossbreeds probably in early stages of pregnancy, some Limousin crosses, possible Belgian Blue. If they were close to calving then the stockman should do a risk assessment for his own safety as well as others based on knowledge of individual observations and temperament records and post advice based on this information. Be surprised if such a detailed protocol exist in farm safety training today.
Fourth photo all Freisian Dairy followers, probably incalf heifers, low risk but highly inquisitive. Risk would be pushing through the animals, and loosing balance, then the herd being frightened the trampling being caused. My advice; always create a pathway with voice or gesticulations.
Ninthace's experience with a parapet path is a classic example where terrain and deviation puts the walker at a disadvantage, fencing strategies should be be part of an automatic safety protocol.
Hope these ideas are not too confusing, might be the year 3026 when they are original thought from the CLA, and only after land gets nationalized.