Exactly what myths are those? Cuz a lot of the nonsense you are posting about H1b taxation are myths in themselves. For H1-Bs there are only two categories Resident Aliens or Non Resident. If he/she is a resident then income taxation is like any other USA person and must pay taxes on their worldwide income, no exception. A non resident alien can claim benefit if there is a treaty between US and that country. The reason being that he person is not a US resident and is using minimal social/infrastructural services or benefits provided by US government and also to avoid double taxation from the home country.
What you are saying about minimum living allowance and sent overseas are urban legends. Never happens.Period. There is no such thing as minimal allowance. There is a minimum salary cap on how much you HAVE TO pay an H-1B visa resident and so what goes to the government as income tax also has a minimum cap. End of story.
Same applies to L1s. L1 visa holders are required to pay
federal income taxes, provided they meet the “substantial presence test” that determines if the person is a resident alien. L1s also have to pay social security and Medicare. There is no arguing about this. There is no way a foreign resident can legally work full time in the US and not have to pay taxes whatever the visa. I dunno where you get your facts from but most of them are malicious and very misleading.