I think the hidden assumption here is that something with a name like Ethereum "Virtual Machine" calls for isolation. This is a misunderstanding about the nature of the EVM.
The EVM is a specification for an ephemeral state machine. the EVM state is derived by processing transactions correctly. Transactions can include the deployment of code and invocations of deployed code. The code itself consists of OPCODES with precise meanings defined in the EVM specification.
Since all Ethereum operations are deterministic, we can say that given an identical initial state and identical inputs, correctly functioning nodes will compute an identical EVM state.
Perhaps another way of understanding this is to think of the EVM as an emergent non-local conclusion of nodes that agree what the EVM state must be.
If one is concerned about the integrity of one's own node, then the node can be run inside a container but such is not a property of the node software itself, e.g. Geth.
Have a look at this: https://www.youtube.com/watch?time_continue=4&v=Za5lPKNV_Mk
Hope it helps.