R编程:当调用本地辅助函数时，允许的递归深度的级别是不同的

this is a purely academic question:
I have recently been working with languages that use tail recursion optimization. For practice I wrote two recursive implementations of sum functions in R, one of them being tail recursive. I quickly realized there is no tail recursion optimization in R. I can live with that. However, I also noticed a different level of allowed depth when using the local helper function for the tail recursion. I have rece