RE, ... why are there often many tiny trades in 'Course of Sales' e.g. 1 or 2 shares per transaction?
This is one reason ...
Share wars: how the robots are robbing you
The prevalence of computer-generated trading in the modern sharemarket has created an unpredictable, and sometimes dangerous, environment for investors.
https://www.smh.com.au/money/investing/share-wars-how-the-robots-are-robbing-you-20120825-24t4t.html
Sharemarkets rigged by trading robots
https://www.smh.com.au/money/sharemarkets-rigged-by-trading-robots-20140426-37avz.html
And ... YES ... The Australian Securities and Investments Commission knows all about it !!
https://asic.gov.au/about-asic/what-we-do/our-role/