I think the reason they are meikel is not because they have a different mehalach halimud. It is an attitude to try and get out of and get away with it the most you can.
If you have a true understanding that you are in this world for avodas hashem it is much easier to be machmir. You understand that avodas hashem is important enough to do lfnim mshuras hadin.
as the gemara in bm 30b says
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