Why do you think so much of the software that ran on large scale computer was custom written by programmers whereas today most personal computer software is purchased off the shall?

In the early days of large-scale computing, software was custom-written to meet specific organizational needs and to leverage unique hardware capabilities, as there were few standardized solutions available. As technology advanced, the market for personal computers grew, leading to the development of standardized software that could cater to a wider audience. This shift allowed software companies to create mass-market applications, making them more accessible and cost-effective for everyday users. Today, the emphasis on user-friendly, off-the-shelf solutions reflects the diverse needs of a broader consumer base, reducing the necessity for custom development.