Membership list (Single constituent) date_modified missing from response

This endpoint: Membership list (Single constituent):

Here's the sample output (and this is the same data I get when I call the API):

{
"count": 2,
"value": [{
"id": "53",
"category": "Young Maestros",
"dues": {
"value": 750
},
"expires": "2002-03-17T00:00:00Z",
"joined": "2000-05-01T00:00:00Z",
"members": [{
"id": "72",
"constituent_id": "261",
"primary": true
}, {
"id": "73",
"constituent_id": "526",
"primary": false
}, {
"id": "74",
"constituent_id": "483",
"primary": false
}],
"program": "Young Explorers",
"standing": "Active",
"subcategory": "Elementary"
}, {
"id": "82",
"category": "Young Maestros",
"dues": {
"value": 750
},
"expires": "2009-04-14T00:00:00Z",
"joined": "2003-01-22T00:00:00Z",
"members": [{
"id": "110",
"constituent_id": "483",
"primary": true
}],
"program": "Young Explorers",
"standing": "Lapsed"
}]
}

But that inner object is supposed to be a MembershipRead object which should have date_added and date_modified fields:

Where are they? Are they missing by design or is this a bug that can be easily fixed?

I'm doing a 2-way sync between systems, and I need to be able to pull memberships by constituent ID or just one membership by ID and get the datemodified timestamp. Is it possible to do that? The membership/v1/memberships/membershipdetails/ID endpoint doesn't return the date_modified field; neither does this one. Is it possible?

Thanks.