I'm very confused by your posts.

What sociopolitical landscape are you talking about? The fact that HK rejoined China twenty years ago? The anti-mainlander sentiment among a large number of people in the SAR? The fact that many people come from Guangdong every day to buy cosmetics, designer goods, milk formula etc to parallel trade back home?

And of course my posts are anecdotal. If you follow the rules, no luggage that eights over 23kg and over certain dimensions is allowed on the East Rail Line. However, in practice, many people (of all races) carry over limit each day.
From my experience in HK, a non-Chinese person has a higher chance of getting something past any security as they are likely to only speak Chinese. The same experience tells me that in TST only people from the Indian subcontinent tend to get stopped by the police.