Maybe those are real concerns in other churches, but in most American churches, the greatest heresies are political activism with a Chrisitan label and "health and wealth" with a Christian label, and neither is legalism. And they don't typically sell heaven or hell, because neither the clergy nor the congregation are eschatalogically oriented, i.e. setting your mind on the afterlife rather than the cares of this world in this mortal life.
However, if they order you to behave in a certain way, unless you do xyz, you won't be accepted as a member, or if you're already a member you'll be excommunicated, that's a discipline issue, not legalism. As matter of fact, churches that run under strict schedules, rules and traditions last longer, a shared identity and solidarity are built among their congregants, you lose yourself and merge into the group. That's not a salvation issue. The reward and punishment are not heaven and hell, but the sense of belonging to community and lack thereof, it's about a collective mindset.