The 1970/71 Ashes was a seven-match series (although one test was abandoned without a ball being bowled). The Aussie board made way for another game in the series: that wouldn't happen now, they'd be too interesting in prioritising the 100
The BBC had an article pointing out that a key difference was extras - England have conceded 60 more than Australia. They conceded 74 in the last test, that's a huge amount.
We have bowlers who keep overstepping and wicket keeper who can't keep up to the stumps, put those two things right and...