Escape Never Would Have Happened in the Early Days
I've been reading a few books on Alcatraz, written by various authors (historians, former guards and former inmates).
One thing that many of them point out, is that the Morris-Anglin escape never would have happened in the early years of prison's history.
The main reason was that the staffing quality wasn't as good as it had been a generation before.
When Alcatraz opened in 1934, its first inmates were really the most hardened and/or troublesome inmates in the federal system. As a result, it was staffed with veteran correctional officers who'd served at places like McNeil Island, Atlanta or Leavenworth. All of them were very tough and quite wise to many of the tricks in the prison.
By the end of the 1950's/beginning of the 1960's, however, these veteran guards had mostly retired or transferred to less stressful postings. Many of the guards who'd replaced them were men who had no prior experience as being prison guards. Some simply had grown up in, and lived in The Bay area and thought working on Alcatraz would be an interesting -and secure- job. Most of them simply didn't have the experience that the early guards had.
As well, the character of the convicts had changed as well. Most of the Alcatraz inmates were no longer the gangsters and gunmen of the 30's who were escape artists. Most of the current sort of Alcatraz inmate of the later era were men who were more disruptive and violent. (Morris and the Anglins, being escape artists were a throwback to an earlier time). As a result, the guards weren't on the lookout for escapes as much as they would have been years earlier. On the Anglin's files, it specifically said they shouldn't be celled next door to each other...but the administration ignored it. It also listed Morris as an escape artist; but again, the administration ignored any warnings and didn't keep as close an eye on him as they clearly should have.
(As an example of how the perceived risk of escapes seemed to have died down: Of the fourteen escape attempts from Alcatraz, ten took place between 1936 and 1946. In the last seventeen years, there were only four; and none happened between 1946 and 1956. So, I think that many of the custodial staff simply weren't on the alert as much as they would have been years earlier.)