Or is it just you don't like the answer?
There are many valid criticisms of polling, unrepresentative sampling being a key one. Further to
@yorkie's general point about the sort of people who answer these polls, it's important to note that the 64% refers to all adults - not those who actually use it. It's very easy to say you'd wear a mask on public transport if you have no intention of using public transport!
It's also worth considering the context under which the poll had been carried out - lots of trumpeting around "freedom day" with plenty of doom & gloom from some quarters alongside rapid growth in the number of positive tests being returned. Several weeks on and with stagnant case numbers and none of the dire forecasts coming true, people will inevitably feel less concerned now than they were in the run up to the 19th July
Whilst looking through the data, I also found an interesting little bit of information. The %age of people who reported seeing "everyone or almost everyone" wearing a face covering whilst out shopping in the previous 7 days has gone from 87% the week ended 4th July to 69% the week ended 25th July (last week of data) - which corresponds to the general reporting here about people beginning to move away from wearing face coverings