lists of RasterLayers behaving weirdly

RasterLayer-list.R

#
# If I wrap a single RasterLayer in a list, I can extract it
# with .[[1]] but not with unlist(). 
#
# This example just uses a single `RasterLayer` to make the point.
# The broader problem (for me) is that it seems to be precluding the
# possibility of using `purrr::map2()` to combine lists of RasterLayers
# in various ways.
#

library(raster)

# Canned example
logo <- raster(system.file("external/rlogo.grd", package="raster"))

# Wrap it in a list
x <- list(logo)

# Works as expected
x[[1]]

# Mystery: still a list ...
unlist(x)  

# TRUE --- but why?
identical(x, unlist(x))

# For reference
sessionInfo()

# R version 3.6.2 (2019-12-12)
# Platform: x86_64-apple-darwin15.6.0 (64-bit)
# Running under: macOS Catalina 10.15.6
# 
# Matrix products: default
# BLAS:   /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib
# LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib
# 
# locale:
#   [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
# 
# attached base packages:
#   [1] stats     graphics  grDevices utils     datasets  methods   base     
# 
# loaded via a namespace (and not attached):
#   [1] compiler_3.6.2