It isn't clear from the article whether the woman was attempting to cross at a crosswalk or mid block. Although this incident took place in the UK, where such a detail may not matter (?) this information would be germane in - for example - Toronto where it is not legal to cross outside of a crosswalk if one is available - the rule of thumb being that one should be 30 metres or more from any crosswalk for the crossing point to be considered as not having a crosswalk available.

"Where there is no crosswalk, it is legal for pedestrians to cross, **so long as one yields to on-coming traffic.**"

Rules for crossing the street - jaywalking - pedestrian traffic signals

There is also the matter of pedestrian right of way. That is, provided she began her crossing legally, i.e yielded to oncoming traffic if crossing mid point or if she began her crossing in a crosswalk with a stop/go signal before the signal flashed to 'stop' - she "may continue the crossing as quickly as reasonably possible."

The next matter is, if she crossed midblock, would she be considered to have yielded to oncoming traffic before stepping out into the road? Twenty miles per hour means one covers (5280 *20) /60 = 1,760 feet in a minute, or 29 feet in a second - assuming the average cross is 7 seconds for the entire width of the road, 3.5 for one lane of same - the oncoming traffic at such a speed should be at least (29 * 3.5) - about 100 feet - again, about 30 meters - away before the pedestrian should attempt such a cross.

It's not clear from the article how far the defendant was from the pedestrian when she stepped into the road, or how far when he first saw her. What the prosecution seems to be pointing out is that even if a pedestrian considers oncoming traffic and attempts a crossing whilst at a safe distance from said traffic, they might still - for example - slip and fall while crossing, thereby taking longer than anticipated to cross and requiring oncoming traffic to brake. This is a moot point if oncoming traffic lacks suitable brakes.